Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tenascin-C is a modular glycoprotein composed of domains of amino acid repeats. All forms of tenascin-C have eight constant fibronectin type III repeats, but additional fibronectin type III repeats can be spliced into a variable domain found between the fifth and sixth constant repeats. Four extra repeats, named A, B, C and D, have been examined previously. Here, we have used in situ hybridization to determine the tissue origins of the novel AD1 and AD2 repeats. In the embryonic-day-10 chicken embryo, transcripts encoding the AD2 repeat are limited to the tips of lung bronchioles and the base of feather buds. In contrast the AD1 hybridization signal was widespread. Quantitative in situ hybridization reveals AD1-containing transcripts represent up to 85% of the total tenascin-C mRNA in some tissues (developing bone), and are undetectable in others (e.g. radial glia). Avian and human tumor cell lines were examined for the expression of the AD1 repeat using the reverse transcriptase polymerase chain reaction (RT-PCR). Transcripts encoding six different tenascin-C splice variants incorporating the AD1 repeat were found in the fibrosarcoma cell line, QT6. Many human tumor cells, including malignant melanoma and ductal breast carcinoma, were positive for AD1 tenascin-C expression. In addition, we found evidence of AD1 tenascin-C expression in samples of excised human tumors. Our results show that a novel variant may be a major part of the tenascin-C of the embryonic extracellular matrix, and may also be found in the stroma surrounding some human tumors.
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PMID:The expression of tenascin-C with the AD1 variable repeat in embryonic tissues, cell lines and tumors in various vertebrate species. 940 2

A cDNA encoding the precursor of one of the major components of gilthead sea bream, Sparus aurata, egg envelope has been cloned by reverse transcriptase polymerase chain reaction (RT-PCR) techniques. The clone was isolated starting from total RNA extracted from the liver of spawning female fish and estradiol-17 beta-treated male fish. Sequence analysis revealed that the cDNA encoded a protein of 405 aa corresponding to 49-kDa component (termed gp49), a glycoprotein belonging to the N-linked type. The gp49 protein is homologous to the Zl-3 of medaka Oryzias latipes, the mammalian ZPC and ZPC homologues of Xenopus laevis (xlZPC) and carp Cyprinus carpio (ccZPC). In addition, the open reading frame also encodes an additional aa sequence, the signal peptide, located in the N-terminal region of the protein. RT-PCR and in situ expression analyses evidenced an organ-restricted pattern: the mRNA was detected only in liver of spawning female and estradiol-17 beta-treated male fish but not in other tissues.
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PMID:Identification and spatial distribution of the mRNA encoding the gp49 component of the gilthead sea bream, Sparus aurata, egg envelope. 940 96

The intestinal sucrase-isomaltase (SI) complex is a glycoprotein of the small intestine brush border membrane that plays an important role in the final degradation of carbohydrate. To clone the chicken SI, we employed reverse transcriptase polymerase chain reaction (RT-PCR). Agarose gel electrophoresis of the PCR products exhibited one amplified band of approximately 800 bp. The fragment was extracted from the gel and sequenced. The cDNA sequence of the chicken SI is 786 bp in length and exhibits 99% identity at the nucleotide level to the Homo sapiens SI mRNA. Using our cDNA as a probe, Northern analysis revealed a transcript of approximately 6.0 kb in chicken jejunum and ileum tissues.
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PMID:Research notes: Identification and isolation of chicken sucrase-isomaltase cDNA sequence. 946 64

Human foamy virus (HFV) is the prototype of the Spumavirus genus of retroviruses. These viruses have a genomic organization close to that of other complex retroviruses but have similarities to hepadnaviruses such as human hepatitis B virus (HBV). Both HFV and HBV express their Pol protein independently of their structural proteins. Retroviruses and hepadnaviruses differ in their requirements for particle assembly and genome packaging. Assembly of retroviral particles containing RNA genomes requires only the Gag structural protein. The Pol protein is not required for capsid assembly, and the Env surface glycoprotein is not required for release of virions from the cell. In contrast, assembly of extracellular HBV particles containing DNA requires core structural protein and polymerase (P protein) for assembly of nucleocapsids and requires surface glycoproteins for release from the cell. We investigated the requirements for synthesis of extracellular HFV particles by constructing mutants with either the pol or env gene deleted. We found that the Pol protein is dispensable for production of extracellular particles containing viral nucleic acid. In the absence of Env, intracellular particles are synthesized but few or no extracellular particles could be detected. Thus, foamy virus assembly is distinct from that of other reverse transcriptase-encoding mammalian viruses.
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PMID:The roles of Pol and Env in the assembly pathway of human foamy virus. 1052 50

The Friend spleen focus-forming virus (SFFV) env gene encodes a 409-amino-acid glycoprotein with an apparent Mr of 55,000 (gp55) that binds to erythropoietin receptors (EpoR) to stimulate erythroblastosis. We reported previously the in vivo selection during serial passages in mice of several evolutionary intermediates that culminated in the formation of a novel SFFV (M. E. Hoatlin, E. Gomez-Lucia, F. Lilly, J. H. Beckstead, and D. Kabat, J. Virol. 72:3602-3609, 1998). A mouse injected with a retroviral vector in the presence of a nonpathogenic helper virus developed long-latency erythroblastosis, and subsequent viral passages resulted in more pathogenic isolates. The viruses taken from these mice converted an erythropoietin-dependent cell line (BaF3/EpoR) into factor-independent derivatives. Western blot analysis of cell extracts with an antiserum that broadly reacts with murine retroviral envelope glycoproteins suggested that the spleen from the initial mouse with mild erythoblastosis contained an array of viral components that were capable of activating EpoR. DNA sequence analysis of the viral genomes cloned from different factor-independent cell clones revealed env genes with open reading frames encoding 644, 449, and 187 amino acids. All three env genes contained 3' regions identical to that of SFFV, including a 6-bp duplication and a single-base insertion that have been shown previously to be critical for pathogenesis. However, the three env gene sequences did not contain any polytropic sequences and were divergent in their 5' regions, suggesting that they had originated by recombination and partial deletions of endogenously inherited MuLV env sequences. These results suggest that the requirements for EpoR activation by SFFV-related viruses are dependent on sequences at the 3' end of the env gene and not on the polytropic regions or on the 585-base deletions that are common among the classical strains of SFFV. Moreover, sequence analysis of the different recombinants and deletion mutants revealed that short direct and indirect repeat sequences frequently flanked the deletions that had occurred, suggesting a reverse transcriptase template jumping mechanism for this rapid retroviral diversification.
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PMID:An array of novel murine spleen focus-forming viruses that activate the erythropoietin receptor. 955 56

Glycodelin is a 28 kDa glycoprotein of the lipocalin family that was previously considered to be specific for the reproductive tract. Glycodelin is found in the secretory glandular epithelium of endometrium and in seminal vesicles. Given the cyclic differentiation of normal endometrial epithelium, we studied by immunohistochemistry a possible expression of glycodelin in other tissues displaying stroma-to-epithelium maturation. We report here that 11/11 biphasic synovial sarcomas expressed glycodelin in the cells exhibiting epithelial or glandular differentiation while the sarcomatous spindle cells remained negative. Glycodelin was also found in secreted material in the lumina of the gland-like structures. In only 1 of the 7 monophasic synovial sarcomas studied, focal glycodelin reactivity was seen in some flattened spindle cells. The expression of glycodelin in biphasic synovial sarcoma tissue was further verified by the demonstration of glycodelin mRNA by reverse transcriptase-polymerase chain reaction. Considering the monoclonal origin of synovial sarcomas, our findings raise the intriguing possibility that activation of expression of the glycodelin gene is involved in the molecular regulation of mesenchyme-to-epithelium differentiation.
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PMID:Epithelial expression of glycodelin in biphasic synovial sarcomas. 959 Jan 22

The macrophage colony-stimulating factor (MCSF) is a 40-76-kD glycoprotein that plays an important role in the activation and proliferation of microglia both in vitro and in injured neural tissue. Here, we examined the regulation of MCSF receptor (MCSFR) and MCSF in the normal and injured mouse central nervous system (CNS) by using confocal laser microscopy, quantitative immunofluorescence, and reverse transcriptase-polymerase chain reaction (RT-PCR) techniques. Immunohistochemistry on fixed, floating tissue sections demonstrated low to moderate MCSFR immunoreactivity (MCSFR-IR) on microglia in the gray and white matter throughout the mouse CNS in the forebrain, brainstem, cerebellum, and spinal cord. High levels of MCSFR-IR were restricted to the superficial layer of the spinal cord dorsal horn, substantia nigra, and area postrema, a CNS region that lacks the blood-brain barrier. CNS injury led to a strong and specific increase in MCSFR-IR in the directly injured dorsal forebrain, in the cervical spinal cord (C2) after transection of the sensory, minor occipital nerve, and in the axotomized facial motor nucleus. Further investigation at the mRNA level in the facial nucleus model showed that this increase was accompanied by a rapid induction of the transcript for MCSFR, with a peak 1-2 days after injury, but only a constitutive expression of MCSF-mRNA. In summary, although normal levels of MCSF receptor in most microglia are low, microglial activation is accompanied by a rapid and massive increase. In view of the constitutive expression of MCSF, the early upregulation of the MCSF receptor may play a central role in preparing these macrophage-related cells to take part in the cellular response to CNS injury.
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PMID:Regulation of MCSF receptors on microglia in the normal and injured mouse central nervous system: a quantitative immunofluorescence study using confocal laser microscopy. 959 28

The chicken oviduct ecto-ATP diphosphohydrolase (ATPDase), a member of the ecto-ATPase family, was purified to homogeneity previously (Strobel, R. S., Nagy, A. K., Knowles, A. F., Buegel, J., and Rosenberg, M. O. (1996) J. Biol. Chem. 271, 16323-16331). It is an 80-kDa glycoprotein with high specific activity (approximately 1,000 micromol/min/mg with MgATP as the substrate) and hydrolyzes both nucleoside triphosphates and diphosphates. Using amino acid sequence information obtained from the purified enzyme, two partial cDNA clones were obtained using reverse transcriptase-polymerase chain reaction and library screening. This is the second ecto-ATPase family member and the first ecto-ATPDase to be cloned from information derived from purified proteins. The deduced primary sequence of the chicken oviduct ecto-ATPDase indicates a protein of 493 amino acid residues with a molecular mass of 54 kDa. The predicted orientation shows it to be anchored to the membrane by two transmembranous segments near the NH2 and COOH termini with very short intracytoplasmic peptides at either end. The bulk of the protein is extracellular and contains 12 potential N-glycosylation sites, several potential phosphorylation sites, and five sequences that are conserved in seven other related membrane proteins. Four of the conserved sequences, designated as apyrase conserved regions, are present in both ecto-ATPases and soluble E-type ATPases. The fifth conserved region, which occurs near the COOH terminus of the eight proteins, is observed only in the membrane-bound ecto-ATPases. Unexpectedly, sequence comparison revealed that the chicken oviduct ecto-ATPDase is equally distant from the two ecto-ATPases, which exhibit low activity toward ADP, and the four putative ecto-ATPDases, which are closely related to CD39.
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PMID:Molecular cloning of the chicken oviduct ecto-ATP-diphosphohydrolase. 963 55

The diversity in selected regions of the transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV) genomes was analyzed among known TGEV and PRCV strains and field isolates. The N-terminal half of the spike (S) glycoprotein gene and open reading frames (ORF) 3, 3-1 and 4 were amplified by reverse transcriptase reaction and polymerase chain reaction (RT/PCR), and analyzed using restriction fragment length polymorphism (RFLP) patterns of the amplified DNA. Reference TGEV strains (Miller and Purdue) and a PRCV strain (ISU-1), and TGEV and PRCV field isolates were analyzed. Based on the size of the ORF 3, 3-1 and 4 RT/PCR products, TGEV and PRCV strains could be quickly and easily differentiated into three groups designated TGEV Miller, Purdue types and PRCV. By RFLP analysis of the N-terminal region of the S glycoprotein gene and ORFs 3, 3-1 and 4, TGEV and PRCV strains were differentiated into five groups using the restriction enzyme Sau3AI. Sequence analysis of a PCR product in the ORFs 3, 3-1 and 4 from virulent and attenuated Miller strains demonstrated additional differences in that region which have been correlated with a change in virulence of TGEV isolates.
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PMID:Field isolates of transmissible gastroenteritis virus differ at the molecular level from the Miller and Purdue virulent and attenuated strains and from porcine respiratory coronaviruses. 963 93

In the absence of envelope gene expression, retrovirus packaging cell lines expressing Moloney murine leukemia virus (MLV) gag and pol genes produce large amounts of noninfectious virus-like particles that contain reverse transcriptase, processed Gag protein, and viral RNA (gag-pol RNA particles). We demonstrate that these particles can be made infectious in an in vitro, cell-free system by the addition of a surrogate envelope protein, the G spike glycoprotein of vesicular stomatitis virus (VSV-G). The appearance of infectivity is accompanied by physical association of the G protein with the immature, noninfectious virus particles. Similarly, exposure in vitro of wild-type VSV-G to a fusion-defective pseudotyped virus containing a mutant VSV-G markedly increases the infectivity of the virus to titers similar to those of conventional VSV-G pseudotyped viruses. Furthermore, similar treatment of an amphotropic murine leukemia virus significantly allows infection of BHK cells not otherwise susceptible to infection with native amphotropic virus. The partially cell-free virus maturation system reported here should be useful for studies aimed at the preparation of tissue-targeted retrovirus vectors and will also aid in studies of nucleocapsid-envelope interactions during budding and of virus assembly and virus-receptor interactions during virus uptake into infected cells. It may also represent a potentially useful step toward the eventual development of a completely cell-free retrovirus assembly system.
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PMID:In vitro cell-free conversion of noninfectious Moloney retrovirus particles to an infectious form by the addition of the vesicular stomatitis virus surrogate envelope G protein. 965 75


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