Podcasts about cdnas

Ira Pastor, ideaXme life sciences ambassador, interviews Dr. Wei-Wu He, Ph.D, Executive Chairman of Human Longevity Inc (HLI). Ira Pastor Comments: The US Centers for Disease Control (CDC) calls chronic degenerative disease “the public health challenge of the 21st Century,” especially as 75% of our healthcare spending is on people with chronic degenerative conditions, which are the leading causes of death and disability. Preventative healthcare consists of measures taken for chronic disease prevention. Disease and disability are affected by numerous factors (including the environment, genetic predisposition, disease causative agents, and lifestyle choices), are dynamic processes which begin before individuals realize they are affected, and if we could intervene earlier, we could have significant impact not only on the deaths that could have been prevented, but also the lifelong disability, compromised quality of life, and burgeoning healthcare costs. Dr. Wei-Wu He: Dr. Wei-Wu He, Ph.D has been serving as the Executive Chairman of Human Longevity Inc (HLI), a company merging extensive amounts of human genotype and phenotype data with machine learning so that it can help develop new ways to fight and prevent diseases associated with aging), since July 2019. Dr. He received his Ph.D. in Molecular Biology from Baylor College of Medicine and received an M.B.A. degree from the Wharton School at University of Pennsylvania. Prior to HLI, Dr. He was the CEO of OriGene Technologies, Inc. a company founded as a research tool enterprise focused on the creation of the largest commercial collection of full-length human cDNAs which helps develop products for pharmaceutical, biotechnology, and academic research, and he remains the chairman of the board of directors. Dr. He also is the founder and General Partner of Emerging Technology Partners, LLC (ETP), a life sciences focused venture fund established since 2000. Dr. He has been involved in founding or funding over 60 biotech companies throughout his career, some of which went on to be acquired by significantly larger firms. In the earlier part of his career, Dr. He was one of the first few scientists at Human Genome Sciences, and prior to that, was a research fellow at Massachusetts General Hospital and Mayo Clinic. Dr. He is an author to more than 30 research publications and inventor of over 32 issued patents. On this episode we will hear from Dr. He about: His Background - how he developed an interest in science, in molecular biology and in cancer biology. Why he transitioned from bio-medical research into venture capital. The HLI "Health Nucleus" program which integrates whole-genome sequencing with advanced imaging and blood metabolomics, to identify adults at risk for key health conditions associated with age-related chronic conditions including cancer, heart disease, diabetes, chronic liver disease, and neurological disorders. The HLI microbiome / virome research focus. HLI's new corporate venture fund initiatives and investments it is making in supportive health and wellness tools. Credits: Ira Pastor interview video, text, and audio. Follow Ira Pastor on Twitter:@IraSamuelPastor If you liked this interview, be sure to check out ourinterview on virtual health with Dr. Sneh Khemka! Follow ideaXme on Twitter:@ideaxm On Instagram:@ideaxme Find ideaXme across the internet including on YouTube, iTunes,SoundCloud,Radio Public,TuneIn Radio,I Heart Radio, Google Podcasts, Spotify and more. ideaXme is a global podcast, creator series and mentor programme. Our mission: Move the human story forward!™ ideaXme Ltd.

GEN Sounds of Science May 1, 2018 GEN recently spoke to Minjun Liu, Ph.D., marketing director for OriGene, for a sponsored podcast. OriGene Technologies was founded as a research tool company focused on the creation of a large commercial collection of full-length human cDNAs in a standard expression vector. Company officials say the firm’s mission is to prepare comprehensive, genome-wide research tools and technology platforms to allow scientists to better study complete biological pathways. The goal is to enable more detailed insights into stem-cell research and into disease mechanisms, such as those that lead to cancer.

The processing of APP occurs in two alternative ways: upon release of the ectodomain by α-secretase, the neuroprotective APPsα-fragment is produced. But if APP is cleaved by the β-secretase the Aβ-peptide can be produced. To be able to influence the production of Aβ-peptides, it is essential to understand how it is decided if cleavage occurs by α- or β-secretase. At present little is known about the control of the alternate processing. Until now, the molecular mechanisms and especially the responsible cellular modulators are not understood in detail or not yet identified. To get a better understanding of cellular regulatory processes and to identify novel cellular modulators of APP ectodomain shedding, the present work chose two approaches: on the one hand cellular mechanisms of TMEM59-mediated inhibition ectodomain shedding of APP were investigated. On the other hand a genome-wide RNAi screening in Drosophila cells was performed in order to identify novel cellular modulators of APP ectodomain shedding in human cells. TMEM59 was identified as a novel modulator of APP ectodomain shedding in a cDNA expression screening in the lab (Neumann et al., 2006; Schobel et al., 2008; Schobel et al., 2006). TMEM59 is a Golgi protein that inhibits on the one hand processing and maturation of APP and on the other hand Golgi glycosylation reactions (Fischer, 2008). My own work could verify these effects of TMEM59 and its homolog TMEM59L on processing and maturation of APP. In particular, it was shown that these effects are not only true for transiently expressed APP but also for endogenous levels of APP. In detailed immunofluorescence studies it was shown that TMEM59 colocalizes with different markers of the Golgi subcompartments and that therefore TMEM59 is present throughout the whole Golgi apparatus. This finding points to a more general modulation of Golgi glycosylation reactions by TMEM59. To test if TMEM59-dependet modulation of Golgi glycosylation reactions also affects APP secretases ADAM10 and BACE1, which are also glycosylated proteins, the activities of these proteases were investigated. It was shown that proteolytic activities were not changed, ruling out that impairment of secretase activities by TMEM59 could cause the observed inhibition of APP processing. But interestingly, studies of intracellular APP transport could show that TMEM59 caused retention of APP in the Golgi apparatus and blockage of transport towards the cell surface and into endosomal compartments. Since APP is cleaved by α-secretase at the plasma membrane and by β-secretase in endosomes it is likely that a TMEM59-dependent APP transport block causes the observed inhibition of APP ectodomain shedding. For further validation of TMEM59 and its homolog TMEM59L as modulators of APP ectodomain shedding, a double knockdown study was performed. In this approach effects on APP ectodomain shedding could also be established, affirming TMEM59 and its homolog TMEM59L as modulators of APP ectodomain shedding with novel cellular mechanisms. In order to identify novel cellular modulators of APP ectodomain shedding a genome wide RNAi screening in Drosophila cells was performed and candidate genes were investigated in human cells in present work. Initially a suitable Drosophila reporter cell line expressing a reporter construct of APP ectodomain shedding (HRP-APP) was established. Other constructs were used to monitor general secretion (GLuc) and transfection efficiency (FLuc). Using Kuzbanian, the α-secretase in Drosophila (Sapir et al., 2005), as a positive control guaranteed that transfection of cDNAs into Drosophila cells did not interfere with uptake of dsRNAs or efficiency of RNAi and that the reporter construct HRP-APP is normally produced and processed in reporter cells. After successful establishment of the reporter cell line the genome wide RNAi was performed in two steps: a primary screening revealed approx. 300 candidate genes out of which 43 could be confirmed in a secondary screening to be modulators of APP ectodomain shedding. The RNAi screening was verified by the several-fold appearance of Kuzbanian among the top modulators. For further investigation of the top candidates human ortholog genes were identified. The 30 human candidate genes were investigated in RNAi studies in human SH-SY5Y cells. In these cells, APP is processed by α-secretase ADAM10 as well as by β-secretase BACE1. Therefore effects on both shedding products (APPsα and APPsβ) were investigated upon depletion of candidate genes using siRNAs. It is known that siRNAs produce a high rate of off target effects, to this end a robust validation strategy was developed. Candidate genes were first depleted with two different siRNA pools and their effects on APP shedding were compared. Afterwards the remaining 12 candidate genes were depleted using single siRNA sequences and the effects were compared to those of the siRNA pool. Only when a reproduction of effects was obtained in a next step correlation of knockdown and phenotype were assessed. Using these steps of validation 5 candidate genes could be verified as modulators of APP shedding in human cells: next to genes coding for a histone protein (HIST1H4C), a ribosomal protein (RPL36AL), a protein of the minor spliceosom (ZMAT5), an unknown gene (METTL16) and the gene VPS24 („vacuolar protein sorting-associated protein 24“), coding for a protein of intracellular protein transport, were identified. VPS24 was chosen for further validation by a pathway analysis. VPS24 belongs to the ESCRT machinery („endosomal sorting complex required for transport“) and therefore participates in endosomal-lysosomal protein transport. In further RNAi studies other members of the ESCRT machinery were depleted in human cells and effects on APP shedding were compared to VPS24 depletion. For most of the ESCRT members a consistent reduction in APPsβ production could be observed. To engross these results VPS24 was depleted by using an alternative RNAi system. With this stable knockdown approach, the knockdown phenotype could be confirmed. This stepwise validation strategy for candidate genes of the initial Drosophila RNAi screening verified VPS24 as a modulator of APP ectodomain shedding in human cells.

In the present study, the equine histamine 4 receptor (eH4R) was cloned, sequenced and pharmacologically characterized. The findings were compared to those, obtained with the human H4R (hH4R). Due to its expression in cells of the immune system, the eH4R provides a promising target for the development of novel therapeutic strategies in allergic diseases, such as Recurrent Airway Obstruction (RAO) and allergic dermatitis in the horse. To clone the eH4R, mRNA was isolated from horse white blood cells and cDNA was synthesized by reverse transcription. Specific primers were used to amplify the eH4R sequence, which was then cloned into pJET1.2/blunt vectors. The open reading frame is 1185 bp long and codes for a 394 amino acid protein which shows 72,9 % homology to the human receptor. The cDNA sequence was published in the NCBI GenBank under the accession number HM015200. To pharmacologically and functionally characterize the eH4R and hH4R, their cDNAs were subcloned into the expression vector pcDNA3.1 and either transfected transiently into COS-7 cells or stably into HEK293 cells. Binding-characteristics were examined by homologous und heterologous competition experiments using the antagonist 3H-pyrilamine or the agonist 3H-histamine as radioligand. High affinity binding of histamine could only be detected in hH4R, but not in eH4R transfected COS-7 cells. Nevertheless, histamine was able to inhibit cAMP-production in stably transfected HEK293 cells via the eH4R and the hH4R. The eH4R expressed in HEK293 cells is coupled to the stimulation of ERK1/2, while the hH4R shows already high constitutive activity. The antagonists JNJ7777120, Thioperamide, Pyrilamine and Diphenhydramine display considerable species-specific differences concerning the affinities between eH4R and hH4R and also vary in their intrinsic activities. Thioperamide, known for its inverse agonism at the hH4R showed agonist behaviour in ERK1/2 regulation. In contrast, the non-selective antagonist Diphenhydramin showed inverse agonist behaviour, which was more pronounced at the hH4R than the eH4R. These findings suggest that there are considerable pharmacological and functional differences between the cloned eH4R and hH4R.

Das Blutgefäßsystem eines Organismus stellt eines der größten Organe des menschlichen Körpers dar. Den Grundbaustein der Gefäße bilden Endothelzellen, die durch eine einfache Zellschicht das gesamte System von innen auskleiden. Bei einer Vielzahl an physiologischen und pathophysiologischen Prozessen, wie beispielsweise dem weiblichen Menstruationszyk¬lus, der Wundheilung, den Entzündungsreaktionen oder aber der Ischämie und der Tumorpro¬gression, spielt das Endothel eine wesentliche Rolle. Die Aktivierung der Endothelzellen wird durch zahlreiche verschiedene Faktoren reguliert, die entweder im Blut zirkulieren, von be¬nachbarten Zellen oder aber auch von Tumorzellen sezerniert werden können. Im Rahmen der vorliegenden Arbeit wurde ein Hochdurchsatz-Screen etabliert, bei dem sich Gene mit einem pro-angiogenen Effekt identifizieren lassen. Hierzu erfolgte die individuelle Transfektion und Expression von 34.596 verschiedenen cDNAs in HEK 293-Zellen. Zur Testung wurden deren konditionierte Medienüberstände auf primäre Endothelzellen (HUVECs) transferiert. Zwei bereits aus der Literatur bekannte pro-angiogene Faktoren, bFGF und VEGF, wurden zur Protokoll-Etablierung als Positivkontrollen eingesetzt. Im Screen konnten insgesamt 13 cDNAs identifiziert werden, die einen pro-angiogenen Ef¬fekt zeigten. Unter ihnen fanden sich auch die zwei Positivkontrollen wieder, was einen direkten Beleg für die Funktionalität des Screens darstellt. Des Weiteren wurden vier bekannte und fünf unbekannte cDNAs identifiziert, bei denen bisher noch kein Zusammenhang mit Angiogenese gezeigt werden konnte. Die vier bekannten Gene kodieren für zytosolisch lokali¬sierte Proteine, deren Expression in verschiedene Säuger-Zellen zur Produktion und Sekretion pro-angiogener Faktoren führt. Im Anschluss an den Screen wurde eines der unbekannten Gene (NM_020746) detaillierter charakterisiert. Dieses Gen kodiert für ein 56,6 kDa großes Protein, das aufgrund erster Funk¬tionshinweise den Namen hSEP (human Stimulator of Endothelial Proliferation) erhielt. Die Expression von hSEP in HEK 293-, sowie in anderen Säuger-Zellen, generierte konditionierte Überstände, welche in Mangelmedium gehaltene Endothelzellen, nicht aber Fibroblasten zum Wachstum stimulieren. Mit Hilfe biochemischer Analysen wurde die Sekretion von hSEP nach der Expression in HEK 293-Zellen nachgewiesen. Besondere Bedeutung bei der Lokali¬sierung des Proteins kam hierbei einer bioinformatisch vorhergesagten C-terminalen Trans¬membrandomäne zu. Die Deletion dieser Domäne erzeugte ein deutlich effektiver sezerniertes Protein-Fragment (SEP1-510), führte allerdings gleichzeitig zu einem signifikanten Rückgang der Wachstums-Stimulation bei HUVECs. Des Weiteren ging die für hSEP nachgewiesene Lokalisierung im Golgi und ER zu Gunsten einer diffusen intrazellulären Verteilung verloren. Um den Wirkungsmechanismus von hSEP aufzuklären, wurden verschiedene Experimente durchgeführt. Expressionsanalysen von HEK 293-Zellen, die hSEP exprimierten, zeigten die Induktion verschiedener pro-angiogener Gene wie beispielsweise IL-8, RANTES und VEGF. Des Weiteren korrelierte die Anwesenheit von hSEP im Überstand nicht reproduzierbar mit der Stimulation von HUVECs. Außerdem gelang es nicht, aktives hSEP-Protein rekombinant zu erzeugen, welches für einen direkten Beweis seiner Funktionalität erforderlich gewesen wäre. Darüber hinaus wurden Hinweise auf eine Ko-Expression von hSEP mit VEGF unter hypoxischen Bedingungen sowie in verschiedenen soliden Tumoren gefunden. In welchen Zusammenhang die Expression dieser beiden Proteine steht, müssen weitere detaillierte Un¬tersuchungen zeigen. Insgesamt ist es denkbar, dass hierdurch neue mögliche therapeutische Ansätze für eine Inhi¬bition bei der Tumorangiogenese eröffnet werden könnten.

Der Eileiter spielt eine bedeutende Rolle im Reproduktionsgeschehen und ist dabei in viele wichtige Prozesse involviert. Er unterstützt durch das Milieu, das er bereit stellt, die Kapazitation der Spermien, die Reifung und die Befruchtung der Eizelle, und er fördert durch sezernierte Faktoren die frühe Embryonalentwicklung. Während des Zyklus durchläuft er deutliche morphologische und histologische Veränderungen, um seinen verschiedenen Aufgaben gerecht zu werden. Da viele Veränderungen in einem Gewebe mit einer Veränderung des Transkriptoms einhergehen, haben wir bovines Eileiterepithel als Ausgangsmaterial für Untersuchungen auf der Ebene der mRNA ausgewählt. Um ein homogenes und definiertes Probenmaterial erhalten zu können, musste die Schlachtung der Tiere zur Probengewinnung zu einem möglichst genau definierten Zykluszeitpunkt stattfinden. Hierfür wurde ein Protokoll zur Tiervorbereitung erarbeitet, mit dessen Hilfe alle Tiere für die Versuche einheitlich ausgewählt und zyklussynchronisiert wurden. Weiterhin wurde ein Entnahmeprotokoll für die Eileiterepithelproben entwickelt, das Schwankungen in der Probenqualität unabhängig von der durchführenden Person minimiert. Zur Untersuchung von Veränderungen des Transkriptoms wurde in einem ersten Ansatz eine Kombination aus subtraktiven cDNA-Banken und radioaktiver cDNA-Array-Hybridisierung verwendet. Zuerst wurde Eileiterepithel (Ampulle und Isthmus gemeinsam) von drei Tieren im Östrus und drei Tieren im Diöstrus untersucht. Insgesamt wurde die Expression von 3072 cDNA-Klonen (1536 cDNAs pro subraktiver Bank, eine Bank pro Zykluszeitpunkt) im Östrus versus Diöstrus verglichen. Dabei konnten 77 verschiedene cDNAs mit signifikanten Konzentrationsunterschieden zwischen den beiden Zykluszeitpunkten identifiziert werden. Davon waren 37 im Östrus und 40 im Diöstrus stärker exprimiert. Die identifizierten Gene wurden in Funktionsklassen eingeordnet. Dadurch konnten vereinfachte „Gene Ontologies“ gebildet werden, die einen Überblick geben, welche biologischen Prozesse und molekularen Funktionen zwischen Östrus und Diöstrus reguliert werden. So sind Gene, die für die Synthese und Sekretion von Proteinen wichtig sind, im Östrus hochreguliert, wohingegen Gene, die Aufgaben in der Regulation der körpereigenen Immunantwort und der Transkription haben, im Diöstrus hochreguliert sind. In einem zweiten Ansatz wurden die gewonnenen Einblicke in die Genexpressions-veränderungen während des Zyklus weiter vertieft. Dazu wurde ein Ovidukt-Array hergestellt, das auf vorangegangene Arbeiten zur Genexpression im Eileiterepithel aufbaute und durch alle cDNAs, die im Vergleich von Eileiterepithel im Östrus zu Diöstrus als differenziell exprimiert auffielen sowie durch einige Kandidatengene, erweitert wurde. Zusätzlich enthielt es, als interne Kontrolle, 94 cDNAs, von denen keine Veränderung der Genexpression im Zyklusverlauf zu erwarten waren. Auf dem Ovidukt-Array befanden sich insgesamt 549 cDNAs von 432 Genen. Mit diesem Array wurden Hybridisierungs-experimente mit bovinen Eileiterproben aus vier verschiedenen Zyklusstadien durchgeführt, jeweils drei Tiere an Tag 0, Tag 3,5, Tag 12 und Tag 18 des Sexualzyklus. Dabei wurden Proben aus Ampulle und Isthmus getrennt voneinander untersucht. Die Auswertung der Hybridisierungsergebnisse ergab 196 differenziell exprimierte Gene. Die mit den Ovidukt-Array erhaltenen Daten konnten die beim Östrus-Diöstrus-Vergleich erhaltenen Ergebnisse sehr gut bestätigen, weiter vertiefen und spezifizieren. Zusätzlich wurden Veränderungen der mRNA-Spiegel ausgewählter Gene durch quantitative Real-time RT-PCR genauer quantifiziert und Lokalisationsstudien im Eileiterepithel mittels in situ Hybridisierung durchgeführt. Weiterhin wurde damit begonnen, Veränderungen auf Proteinebene in den Eileiterepithelzellen im Zyklusverlauf für einzelne Kandidatengene zu untersuchen. Die vorliegende Arbeit ergab grundlegende Erkenntnisse zur Veränderung der mRNA-Zusammensetzung während des Sexualzyklus im bovinen Eileiterepithel aus der Ampulle und dem Isthmus. Damit wurden histologische Veränderungen des Epithels während des Zyklus auf molekularer Ebene charakterisiert. Auf dieser Grundlage können auch spezifische Reaktionen, die von anwesenden Spermien, befruchteten Eizellen oder Embryonen ausgelöst werden, untersucht werden.

Das Ziel der Arbeit bestand darin, anhand molekulargenetischer Untersuchungen das krankheitsverursachende Gen für das Myoklonus-Dystonia-Syndrom (MDS) in den vorliegenden MDS-Familien zu identifizieren. Außerdem sollte die Vererbung dieses Gens und die molekularen Ursachen seiner allelspezifischen Expression analysiert werden, um einen Beitrag zur Erforschung der genetischen Ursachen des MDS zu leisten. Mit einem positionellen Klonierungsansatz sollte das krankheitsverursachende Gen für das MDS identifiziert werden. Kopplungsanalysen des MDS auf Chr. 7q21 - 22 waren dafür eine wesentliche Voraussetzung. In der Kandidatenregion sollten mit Hilfe eines Annotationsprogramms bekannte und neue Gene identifiziert und eine vollständige Transkriptkarte von diesem Bereich erstellt werden. Neu vorhergesagte Gene mussten experimentell verifiziert und vervollständigt werden. Eine Mutationsanalyse der identifizierten Kandidatengene für das MDS sollte vorgenommen werden. Die Vererbung des MDS erfolgte nach einem dominanten Erbschema, das jedoch keine vollständige Penetranz besitzt. Familienstammbaumanalysen zeigten, dass die Transmission der Erkrankung abhängig vom Geschlecht des krankheitsübertragenden Elternteils ist. Daher sollte eine mögliche genomische Prägung des in MDS-Patienten mutierten Gens in genomischer DNA und auf transkriptioneller Ebene untersucht werden. Die differentielle Methylierung von Cytosinen in CpG-Dinukleotiden ist ein epigenetischer Mechanismus zur Prägung von Genen und kann der Identifizierung geprägter Gene dienen. Die Etablierung der genomischen Bisulfitsequenzierung war die Voraussetzung, um den Methylierungsstatus von CpG-Dinukleotiden im Promotorbereich von SGCE in Lymphoblasten und Gehirngewebe zu analysieren. Die maternale Prägung des SGCE-Gens sollte auf Expressionsebene verifiziert werden. Eine monoallelische Expression des SGCE-Gens wurde in cDNA von genomisch heterozygoten SGCE-Mutationsträgern untersucht. Die differentielle Expression der elterlichen Allele sollte in cDNAs uniparentaler Disomien von Chromosom 7 überprüft werden. Da einige geprägte Gene physikalisch gekoppelt vorliegen, wurden benachbarte Gene auf monoallelische Expression analysiert. Um einen besseren Einblick in die Vererbung des MDS zu bekommen, sollte der Fall einer maternalen Transmission näher untersucht werden, der im Widerspruch zu einer maternalen Prägung des Krankheitsgens steht.

This investigation is based on the identification of cDNA sequence information for a putative chicken homologue of the mammalian cytokine “B cell activating factor belonging to the TNF family” (BAFF) in a chicken EST-database. The cDNAs encoded for the complete open reading frame of chicken BAFF (chBAFF) including a transmembrane domain and a potential furine cleavage side. ChBAFF shows an uncommon high amino-acid sequence identity with 76% identity to human BAFF in comparison with other chicken cytokines. To investigate its biochemical and functional properties, recombinant prokaryotic chBAFF was generated in E. coli and eukaryotic chBAFF was obtained from transfected 293T cells. A polyclonal rabbit antiserum raised against His-chBAFF reacted with both, the prokaryotic and the eukaryotic cytokine and was used to quantify 293T cell derived chBAFF in an ELISA system. Studies by northern blot analysis revealed a strong expression signal in the Bursa of Fabricius and a weak signal in the spleen, while all other tissues including thymus and gut tissue were negative. In situ hybridisation detected a wide distribution pattern for chBAFF-mRNA in all areas of the bursa of Fabricius. However, the strongest expression was seen in the medulla from bursal follikels. These studies indicate that both the bursal stroma and bursal B-cells must be considered as potential sources for chBAFF. To identify target cells for this cytokine, chBAFF receptor(s) expression was investigated in binding studies with Flag tagged chBAFF (Flag-chBAFF) and binding was analysed by flow cytometry. Receptor expression was clearly restricted to B-cells including mature B-cells from peripheral lymphoid organs as well as immature bursal B-cells. Subsequent studies on the ontogeny of chBAFF receptor expression showed a positive correlation between the cytokine receptor expression and the expression of the B-cell antigen receptor in the developing embryonic bursa. Receptor-ligand-interaction ELISA and co-immunoprecipitation experiments demonstrated that chBAFF binds to all three mammalian BAFF receptors identified thus far. Importantly, studies of chBAFF binding to the chicken B-cell line DT40 showed that an engineered soluble form of the human BAFF-receptor BCMA (huBCMA-Fc) inhibited chBAFF binding. The addition of 293T cell derived chBAFF to splenic lymphocyte cultures led to a significant increase in B-cell viability. This dose-dependent effect was also observed in lymphocyte cultures from ceacal tonsils and in cultures of purified (>95%) splenic B-cell preparations. While the rapid apoptosis in cultures of bursal lymphocytes could not be completely prevented, chBAFF clearly increased the survival of these immature B-cells. CFSE labelling experiments further showed that chBAFF did not induce B-cell proliferation. Therefore, it is highly probable that chBAFF, as its mammalian counterpart, is a potent inhibitor of B-cell apoptosis. These in vitro studies were complemented by in vivo experiments with purified prokaryotic chBAFF. Daily injection of recombinant cytokine for 7 days induced a significant increase in spleen weight and B-cell frequency in spleen and caecal tonsils. Besides, the functional overexpression of chBAFF induced significantly (4-fold) increased serum IgM levels. Therefore, chBAFF does not only increase B cell numbers, it also influences their differentiation to antibody secreting cells. However, no effect was observed on the bursa of Fabricius prompting the reverse experimental approach. With the availability of a soluble cytokine specific receptor (huBCMA-Fc) in vivo knockdown studies could be performed. Daily i.p. application of huBCMA-Fc to newly hatched birds for 5 days led to decreased spleen weights and drastically reduced the B-cell frequency in spleens and caecal tonsils. In addition, bursal weights in treated birds were lower than in untreated controls. This experiment in combination with the observation of high expression levels of chBAFF-mRNA in the bursa and functional BAFF-receptor(s) on bursal B-cells strongly indicated a thus far unknown role for BAFF in early B-cell development.

Among the Paramyxoviridae, only members of the subfamily Pneumovirinae like Respiratory Syncytial Virus (RSV) encode two nonstructural proteins, NS1 and NS2. These two proteins cooperatively mediate type I interferon resistance and prevent induction of interferon in infected cells. Interactions of NS1 and NS2 proteins in every combination were shown by using the yeast-two-hybrid system. Therfore, NS1 and NS2 are able to form homo- and hetero(oligo)mers in infected cells. Although RSV replicates exclusively in the cytoplasm, NS-Proteins are localized in the cytoplasm as well as in the nucleus. Expression of an enlarged NS1 fusion protein, EGFP-NS1-BRSV N, resulted in the same nuclear and cytosolic localisation indicating that nuclear localisation is not due to diffusion but rather to an active transport. Thus, NS-Proteins should have particular functions in the nucleus of infected cells. Furthermore, yeast-two-hybrid screening of a lung cDNA expression library using NS1 of bovine RSV (BRSV) as a bait, identified cDNA clones encoding several nuclear proteins and one cytosolic protein. BRSV NS2 protein and NS-Proteins from other pneumoviruses (HRSV, PVM) were also able to interact with the identified cellular proteins in yeast. The isolated cDNAs encode the nuclear proteins CDK4BP (p34SEI-1 or TRIP-Br1), RanBP16, MM-1, DEAD Box Helicase p68 and the cytosolic β-COPI. Specific interactions were determined by mutational analysis of BRSV NS1 in yeast. Co-immunoprecipitation from lysates of eukaryotic cells confirmed the interaction of both BRSV NS-Proteins with the cellular proteins. The interaction of MM-1 and p68 with both NS-Proteins was also shown in GST pull down assay in vitro. Engineered BRSV encoding a truncated p68 showed accelerated replication in MDBK and Vero cells, whereas growth of NS1/NS2 deletion mutants expressing the truncated p68 was unaffected. This indicates that the presence of NS-Proteins is a prerequisite for the acceleration of BRSV growth by truncated p68. Furthermore, replication of BRSV was attenuated on HeLa cells in which expression of p68 was knocked down by specific siRNA, whereas replication of the unrelated Rabies virus was not. Thus, p68 is a nuclear target protein for the NS-Proteins and supports BRSV replication in vitro. Growth and division of host cells is necessary for optimal BRSV replication and like p68, most of the identified nuclear protein interactors are related to regulation of the cell cycle and cell division, respectively. Therefore, NS-Proteins appear to influence the cell cycle for optimal replication of BRSV by targeting such proteins. Hence, with the yeast-two-hybrid system, the first cellular interaction partners were identified indicating new functions of NS-Proteins in the viral replication cycle.

Background: For a diploid organism such as human, the two alleles of a particular gene can be expressed at different levels due to X chromosome inactivation, gene imprinting, different local promoter activity, or mRNA stability. Recently, imbalanced allelic expression was found to be common in human and can follow Mendelian inheritance. Here we present a method that employs real competitive PCR for allele-specific expression analysis. Results: A transcribed mutation such as a single nucleotide polymorphism ( SNP) is used as the marker for allele-specific expression analysis. A synthetic mutation created in the competitor is close to a natural mutation site in the cDNA sequence. PCR is used to amplify the two cDNA sequences from the two alleles and the competitor. A base extension reaction with a mixture of ddNTPs/ dNTP is used to generate three oligonucleotides for the two cDNAs and the competitor. The three products are identified and their ratios are calculated based on their peak areas in the MALDI-TOF mass spectrum. Several examples are given to illustrate how allele-specific gene expression can be applied in different biological studies. Conclusions: This technique can quantify the absolute expression level of each individual allele of a gene with high precision and throughput.

Development of an expression cloning system in primary cardiomyocytes - Validation of Translin as a new target for heart failure Congestive heart failure continues to represent a life threatening disease with unmet medical need. Functional impairment of the insufficient heart is reflected in altered geometry of the left ventricle. On the cellular level, cardiac myocytes respond to the increased biomechanical stress by different processes including sarcomeric remodelling and changes in cell shape. In order to identify new regulator genes for sarcomeric rearrangement, we developed an expression cloning system in primary cardiomyocytes. A normalized human heart library was integrated in an inducible adenoviral vector system. After transduction of cardiomyocytes and induction of the transgenes, cells were analyzed for morphological changes reflecting the hypertrophic process. A new system based on laser scanning cytometry was developed as read out. We managed to screen hundreds of cDNAs leading to the discovery of the new target protein Translin. Its overexpression caused the hypertrophic elongation of cardiomyocytes in vitro and could be involved in the pathologic regulation of posttranscriptional RNA processes. These data correlated with the upregulation of Translin in the diseased state of the human heart in vivo. In conclusion, this cell based screen led to the functional characterization of a novel regulator of heart disease providing a basis for the development of innovative drugs for the causative treatment of the insufficient human heart.

Ziel dieser Arbeit war es, Veränderungen innerhalb weniger Stunden nach UV-B-Exposition auf Protein- und Transkriptionsebene bei 10-wöchigen Buchensämlingen Fagus sylvatica L. zu analysieren. Dazu wurden Buchensamen unter standardisierten Bedingungen angezogen und von dem Zeitpunkt der Keimung an unter einem UV-B/PAR-Verhältnis exponiert, das den natürlichen Umweltbedingungen sehr ähnlich ist. Die UV-B-Exposition der 10-wöchigen Buchensämlinge erfolgte in einer UV-B-Pflanzenkammer, die das Lichtspektrum des Sonnenlichts simulierte. Die in einer Zeitkinetik geernteten Primärblätter dienten als Ausgangsmaterial für die Daten in der vorliegenden Arbeit. Die 2D-PAGE der löslichen Gesamtproteine und in vitro translatierten Proteine wurde stets zweifach durchgeführt und jeweils die Gele mit der besten Auflösung als Einzelbestimmung ausgewertet. Die Untersuchungen auf Ebene des löslichen Gesamtproteins der Buche Fagus sylvatica L. erfolgten mittels einer Zeitkinetik über 1 Woche, wobei täglich 1 mal geerntet wurde. Die 2DPAGE Analyse ergab über die gesamte Zeitkinetik betrachtet 1 UV-B-induziertes Protein gegenüber der Starklicht-Kontrolle: Protein 28 (17 kDa; pI 6,8). Die 2D-Analysen auf löslicher Gesamtproteinebene stimmten mit den Daten auf in vitro Translationsebene überein, wobei die Effekte auf Transkriptionsebene wesentlich stärker waren. Insbesondere nach 3 und 6 h UV-B-Exposition konnten auf Transkriptebene eine 60%-ige und 90%-ige Reprimierung gezeigt werden. Diese Reprimierung war transient und auf Proteinebene in geringerem Ausmaß zeitlich verzögert nachzuweisen. Diese Daten gaben Hinweise dafür, daß bei der Buche Fagus sylvatica L. infolge UV-B-Exposition eine Regulation auf Transkriptionsebene stattgefunden hat und die drastische Reprimierung der Transkripte verschiedener Gene nur transient war. Da diese Effekte auf Proteinebene wesentlich schwächer waren, deutete das darauf hin, daß sich die Buchensämlinge innerhalb weniger Stunden an die UV-B-Exposition adaptierten. Auf in vitro Translationsebene gab es bei der Buche Fagus sylvatica L. 18 mRNAs, die unter Berücksichtigung der UV-B- und Starklicht-Tagesgänge direkt dem UV-B-Effekt zugeordnet werden konnten. Es wurde belegt, daß infolge erhöhter UV-B-Exposition 10 Transkripte neu vorhanden waren und die Transkripte von 8 Proteinen nicht mehr nachgewiesen werden konnten. Diesen charakteristischen Veränderungen unterlagen überwiegend saure und basische Proteine. Die Effekte waren zu unterschiedlichen Zeitpunkten der Kinetik zu sehen (7 h, 10 h, 18 h, 28 h und 31 h nach Versuchsbeginn). Die DDRT-PCR wurde eingesetzt, um UV-B-vermittelte Antworten auf Genebene in Buchenblättern zu identifizieren. Bei den isolierten cDNAs wurden geringe Homologien verschiedener Buchenklone in der TIGR-Arabidopsis thaliana-EST-Datenbank gefunden: UV-Breprimierte Buchenklone zeigten Ähnlichkeiten zur Peroxidase, zur „DNA directed RNA-Polymerase alpha chain“ und zu einem „ara-3, ras-related GTP-binding protein“. Durch UV-B-Exposition induzierte Buchenklone wiesen Homologien zu dem „ABI-3“, zu dem „phytochrome regulated gene“ und zur Squalen-Synthase auf. Die Sequenzen dieser Buchenklone wurden zum ersten Mal beschrieben. Erstmals wurde ein ribosomaler Klon L37 bei der Buche beschrieben. Die L37 mRNA wurde aufgrund erhöhter UV-B-Exposition transient induziert. Bei erhöhter Ozon-Behandlung erreichte das Transkript dieses Klons zwei zeitlich voneinander getrennte Maxima; das zweite Maximum (am 3. Tag der Behandlung, 1,6-fache Induktion) ging mit sichtbaren Ozon- Schäden an den jungen Seitentrieben der Buche einher. Die Funktion dieses Proteins ist bisher noch unbekannt. Für eine direkte Zuordnung der isolierten Klone zu den Proteinspots auf der 2D-PAGE müßte eine Sequenzierung der Proteinspots erfolgen. Die Menge der Proteinspots für eine Proteinsequenzierung war jedoch nicht ausreichend. Über die TIGR-Arabidopsis thaliana-EST-Datenbank wurde erstmalig ein nach UV-BExposition induzierter Buchenklon isoliert, der hohe Homologien zum „nascent polypeptide associated complex alpha chain“ aufwies. Dieses Transkript wurde bereits nach 3 h UV-BExposition transient induziert. Der durch Ozon-Exposition reprimierende Effekt wurde durch die kombinierte UV-B/Ozon-Exposition aufgehoben. Die UV-B-vermittelte Induktion dieser zwei Buchenklone unterstützten die auf der 2D-PAGE Analyse resultierende Hypothese, daß die Regulation nach UV-B-Exposition vor allem auf Transkriptionsebene stattzufinden scheint. Die Daten der vorliegenden Arbeit ergaben folgende Schlußfolgerungen: Das Differentielle Display wurde eingesetzt, um infolge UV-B-Exposition differentielle cDNAs in Buchenblättern zu klonieren. Mittels der durchgeführten Northern-Blots wurde gezeigt, daß die Veränderungen auf Transkriptebene durch erhöhte UV-B-Exposition bedingt waren. Die vorliegenden Daten belegten, daß 6 verschiedene Transkripte infolge UV-B-Exposition transient induziert wurden. Diese überwiegenden transienten Veränderungen wurden ebenso durch die Untersuchungen mittels 2D-PAGE auf löslicher Gesamtprotein- und Transkriptebene bestätigt. Das bedeutet, daß innerhalb kurzer Zeit eine Anpassung der Buche an die veränderten Umweltbedingungen erfolgte. Möglicherweise kann dies durch die Anzucht der Buchensämlinge unter UV-B und Schwachlicht begründet werden. Diese Bedingungen sind jedoch umweltrelevant, da die Pflanze in jungen Jahren unter schattigen Lichtbedingungen heranwächst. In der vorliegenden Arbeit wurden infolge abiotischer Streßbehandlung (erhöhtes UV-B) erstmals 2 eindeutig transient induzierte differentielle Buchenklone isoliert: der ribosomale Klon L37 und der „nascent polypeptide associated complex alpha chain“ Klon. Die durchgeführten Northern-Blot Analysen zeigten, daß sich diese 2 Klone als Kandidaten für Molekulare Marker zum Nachweis frühzeitiger UV-B-vermittelter Änderungen auf Transkriptebene bei Fagus sylvatica L. eignen.

Bovine rotavirus (BRV) V1005, like 34 further cell culture-adapted strains in a 6-year survey in Upper Bavaria, Germany, is not a P12 but a P5 P-type rotavirus. The conclusion is based on dot blot hybridization with P1-, P5-, and P11-specific cDNAs, encompassing the VP8* region of major sequence diversity, and on PCR using P1-, P5-, and P11-specific primer pairs derived from the VP5* region of VP4 (VP5* and VP8*, respectively, are the larger and smaller tryptic cleavage products of VP4). Sequencing of the hyperdivergent region of VP4 confirmed the close relatedness of BRV V1005 to BRV UK, the P5 prototype virus

The rat HNF-3 (hepatocyte nuclear factor 3) gene family encodes three transcription factors known to be important in the regulation of gene expression in liver and lung. We have cloned and characterized the mouse genes and cDNAs for HNF-3α, β, and γ and analyzed their expression patterns in various adult tissues and mouse embryonic stages. The HNF-3 proteins are highly conserved between mouse and rat, with the exception of the amino terminus of HNF-3γ, which in mouse is more similar to those of HNF-3α and β than to the amino termini of the rat HNF-3γ protein. The mouse HNF-3 genes are small and contain only two or three (HNF-3β) exons with conserved intron-exon boundaries. The proximal promoter of the mouse HNF3β gene is remarkably similar to that of the previously cloned rat HNF-3β gene, but is different from the promoters of the HNF-3α and γ genes. The mRNA distribution of the mouse HNF-3 genes was analyzed by quantitative RNase protection with gene-specific probes. While HNF-3α and β are restricted mainly to endoderm-derived tissues (lung, liver, stomach, and small intestine), HNF-3γ is more extensively expressed, being present additionally in ovary, testis, heart, and adipose tissue, but missing from lung. Transcripts for HNF-3β and α are detected most abundantly in midgestation embryos (Day 9.5), while HNF-3γ expression peaks around Day 15.5 of gestation.

cDNAs coding for the full-length human 65 and 67 kDa glutamic acid decarboxylases (GAD65 and GAD67) were amplified from pancreas and hippocampus cDNA libraries by polymerase chain reaction, respectively. Both cDNAs were inserted into a baculovirus vector which mediated highly efficient expression of the human GAD65 and GAD67 with histidine-hexapeptides as affinity ligands at their C-termini in Spodoptera frugiperda (Sf9) cells. The recombinant GAD proteins were purified to homogeneity by affinity chromatography using a metal-chelating matrix. The infected Sf9 insect cells expressed the recombinant human GAD65 and GAD67 with natural-like conformations, as confirmed by measurement of their enzyme activities as well as their fully restored autoantigenicities. Immunoprecipitation of metabolically labeled infected Sf9 cells demonstrated the autoantigenic potential of the recombinant GAD proteins. The practicability of using recombinant GAD65 and GAD67 derived from the baculovirus expression system for the development of an immunoassay for the diagnosis of insulin-dependent diabetes mellitus is discussed.

We have isolated and characterized cDNAs from Hydra which encode antistasin, a potent inhibitor of factor Xa in the vertebrate blood clotting cascade. Hydra antistasin is expressed in gland cells and represents a major class of transcripts from Hydra's head. Sequence analysis revealed that Hydra antistasin contains 6 internal repeats of a 25–26 amino acid sequence with a highly conserved pattern of 6 cysteine and 2 glycine residues identical to that in leech antistasin. Conservation of antistasin in a lower metazoan provides a potential link between the vertebrate and invertebrate coagulation systems.

Complementary DNAs encoding three novel and distinct beta subunits (CaB2a, CaB2b and CaB3) of the high voltage activated (L-type) calcium channel have been isolated from rabbit heart. Their deduced amino acid sequence is homologous to the beta subunit originally cloned from skeletal muscle (CaB1). CaB2a and CaB2b are splicing products of a common primary transcript (CaB2). Northern analysis and specific amplification of CaB2 and CaB3 specific cDNAs by polymerase chain reactions showed that CaB2 is predominantly expressed in heart, aorta and brain, whereas CaB3 is most abundant in brain but also present in aorta, trachea, lung, heart and skeletal muscle. A partial DNA sequence complementary to a third variant of the CaB2 gene, subtype CaB2c, has also been cloned from rabbit brain. Coexpression of CaB2a, CaB2b and CaB3 with alpha 1heart enhances not only the expression in the oocyte of the channel directed by the cardiac alpha 1 subunit alone, but also effects its macroscopic characteristics such as drug sensitivity and kinetics. These results together with the known alpha 1 subunit heterogeneity, suggest that different types of calcium currents may depend on channel subunit composition.

We have characterized cDNA clones representing mouse CREB (cyclic AMP responsive element binding protein) mRNA isoforms. These include CREBA and CREBa, of which the rat and human homologues have been previously identified. Both encode proteins with CREbinding activity and identical transactivation potential. The additional CREB mRNA isoforms potentially encode CREB related proteins. From the structural organization of the mouse CREB gene we conclude that the multiple transcripts are generated by alternative splicing. Furthermore we show that specific CREB mRNA isoforms are expressed at a high level in the adult testis. Expression of these isoforms is induced after commencement of spermatogenesis. In situ hybridization suggests that this expression occurs predominantly in the primary spermatocytes. Comparison of the CREB gene with the recently isolated CREM (cAMP responsive element modulator) cDNAs illustrates that the two genes have arisen by gene duplication and have diverged to encode transcriptional activators and repressors of the cAMP signal transduction pathway.

Agrin is thought to mediate the motor neuron-induced aggregation of AChRs and AChE on the surface of muscle fibers at neuromuscular junctions. We have isolated a cDNA from a chick brain library that, based on sequence homology and expression experiments, codes for active agrin. Examination of the sequence reveals considerable similarity to homologous cDNAs previously isolated from ray and rat libraries. A conspicuous difference is an insertion of 33 by in chick agrin cDNA, which endows the encoded protein with AChR/AChE aggregating activity. Homologous transcripts having the 33 by insertion were detected in the ray CNS, which indicates that an insertion of similar size is conserved in agrin in many, if not all, vertebrate species. Results of in situ hybridization studies and PCR experiments on mRNA isolated from motor neuron-enriched fractions of the spinal cord indicate that, consistent with the agrin hypothesis, motor neurons contain transcripts that code for active agrin.

We isolated two cDNAs that encode isoforms of agrin, the basal lamina protein that mediates the motor neuron-induced aggregation of acetylcholine receptors on muscle fibers at the neuromuscular junction. Both proteins are the result of alternative splicing of the product of the agrin gene, but, unlike agrin, they are inactive in standard acetylcholine receptor aggregation assays. They lack one (agrin-related protein 1) or two (agrin-related protein 2) regions in agrin that are required for its activity. Expression studies provide evidence that both proteins are present in the nervous system and muscle and that, in muscle, myofibers and Schwann cells synthesize the agrin-related proteins while the axon terminals of motor neurons are the sole source of agrin.

Serum amyloid A (SAA), a chemically polymorphic protein, is the most sensitive marker protein of the acute phase and the precursor of reactive amyloidosis, which is characterized by deposits of amyloid A protein (AA). We investigated the variability of the SAA gene family in one individual by sequencing 11 SAA-specific clones from an acute-phase-liver cDNA library. At least five different SAA variants were deduced from six different cDNAs. The 3' untranslated gene segments fall into two groups, based on nucleotide sequence and variability in length. Various nucleotide and amino acid substitutions were found predominantly in the 3' portion. Some of these substitutions are unique and increase the number of SAA variants in one individual to at least five. Moreover, genomic DNA of four individuals was examined by analysis of restriction-fragment length polymorphism. Besides two conserved strongly labelled bands, additional polymorphic bands were observed, indicating isotypic and/or allotypic SAA variations. Finally, three different mRNA species were detected by Northern-blot analysis, a finding that might be of relevance for the stability of SAA transcripts.

The pregnancy-specific glycoprotein (PSG) genes constitute a subgroup of the carcinoembryonic antigen (CEA) gene family. Here we report the cloning of four cDNAs coding for different members of the PSG family from a human fetal liver cDNA library. They are derived from three closely related genes (PSG1, PSG4 and PSG6). Two of the cDNA clones represent splice variants of PSG1 (PSG1a, PSG1d) differing in their C-terminal domain and 3′-untranslated regions. All encoded proteins show the same domain arrangement (N-RA1-RA2-RB2-C). Transcripts of the genes PSG1 and PSG4 could be detected in placenta by hybridization with gene-specific oligonucleotides. Expression of cDNA in a mouse and monkey cell line shows that the glycosylated PSG1a protein has a Mr of 65–66 kD and is released from the transfected cells. Sequence comparisons in the C-terminal domain and the 3′-untranslated regions of CEA/PSG-like genes suggests a complex splicing pattern to exist for various gene family members and a common evolutionary origin of these regions

Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is composed of two different subunits, GapA and GapB. cDNA clones containing the entire coding sequences of the cytosolic precursors for GapA from pea and for GapB from pea and spinach have been identified, sequenced and the derived amino acid sequences have been compared to the corresponding sequences from tobacco, maize and mustard. These comparisons show that GapB differs from GapA in about 20% of its amino acid residues and by the presence of a flexible and negatively charged C-terminal extension, possibly responsible for the observed association of the enzyme with chloroplast envelopes in vitro. This C-terminal extension (29 or 30 residues) may be susceptible to proteolytic cleavage thereby leading to a conversion of chloroplast GAPDH isoenzyme I into isoenzyme II. Evolutionary rate comparisons at the amino acid sequence level show that chloroplast GapA and GapB evolve roughly two-fold slower than their cytosolic counterpart GapC. GapA and GapB transit peptides evolve about 10 times faster than the corresponding mature subunits. They are relatively long (68 and 83 residues for pea GapA and spinach GapB respectively) and share a similar amino acid framework with other chloroplast transit peptides.

p38/synaptophysin is a membrane protein present in clear (synaptic) vesicles of neurons and endocrine ceHs [1-4]. From the amino acid sequence deduced from cDNAs encoding p38/synaptophysin, a model with several membrane spanning polypeptide segments and a carboxy-terminal protein domain exposed to the cytoplasmic surface has been constructed [5-7]. The function of p38/synaptophysin is not known. It has been suggested to form a transmembrane channel for ions, or to interact with cytoplasmic factors via its cytoplasmic domain [7]. Since synaptophysin binds Ca2 +, it may also play a role in the release of neurotransmitters stored in clear (synaptic) vesicles [3]. Recently it has been reported [8] that p38/synaptophysin also occurs in hormone containing large dense core vesicles. This would imply that p38/synaptophysin could fulfill similar functions as described above in chromaffin and other secretory ceHs containing large dense core vesicles. In dear (synaptic) vesicles p38/synaptophysin constitutes 7.51Jfo of the vesicle membrane proteins [I]. The amount of p38/synaptophysin in large dense core vesides is not known. Here we report on the quantification of p38/synaptophysin in highly purified chromaffin secretory vesides

Antigen HLA-B27 is a high-risk genetic factor with respect to a group of rheumatoid disorders, especially ankylosing spondylitis. A cDNA library was constructed from an autozygous B-cell line expressing HLA-B27, HLA-Cw1, and the previously cloned HLA-A2 antigen. Clones detected with an HLA probe' were isolated and sorted into homology groups by differential hybridization and restriction maps. Nucleotide sequencing allowed the unambiguous assignment of cDNAs to HL4-A, -B, and -C loci. The HLA-B27 mRNA has the structural features and the codon variability typical of an HLA class I transcript but it specifies two uncommon amino acid replacements: a cysteine in position 67 and a serine in position 131. The latter substitution may have functional consequences, because it occurs in a conserved region and at a position invariably occupied by a species-specific arginine in humans and lysine in mice. The availability of the complete sequence of HLA-B27 and of the partial sequence of HLA-Cw1 allows the recognition of locus-specific sequence markers, particularly, but not exclusively, in the transmembrane and cytoplasmic domains.