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)

The results of studies of a co-carcinogenic effect of two human infectious viruses in tissue culture are reported here. Viable vaccinia virus actively replicating in the cells of primary BALB/c tissue culture and in a number of continuous murine cell lines has been shown to induce in them expression of major structural p30 protein of murine retroviruses. Vaccinia virus has been also shown to cause biochemical transformation of murine cells. Evidence for the capacity of herpes simplex virus type 2 to induce malignant transformation of BALB/3T3 murine cell line has been obtained and confirmed by transplantation to mice. Transformed cell clones did not contain complete infectious herpes simplex virus but were resistant to superinfection with this virus. N-tropic endogenous murine retrovirus of C type with buoyant density in the saccharose density gradient of 1.18 g/cm3 and a reverse transcriptase activity was expressed in the transformed cells. In the virion structure six proteins typical of these viruses with the prevalence of p30 have been demonstrated. Competitive radioimmunoassay revealed a very high level of virus production: p30 level reached 7500 ng p30 R-MuLV per mg of viral protein. Specificity of this results was shown in control experiments.
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PMID:In vitro studies of a co-carcinogenic effect of vaccinia and herpes group viruses. 627 May 80

A human type C retrovirus [human T-cell leukemia (lymphoma) virus; HTLV], recently isolated from young adult patients with cutaneous T-cell lymphoma or leukemia, was not detectably related to other known animal retroviruses in molecular hybridization studies, by comparison of reverse transcriptase and the major core protein p24. The p24 core protein was purified to homogeneity. The amino acid composition, the COOH-terminal amino acid, and the NH(2)-terminal amino acid sequence of the first 25 residues of this major internal structural protein were determined. These results were then compared to the known structure of the internal core protein of other retroviruses. The compositional data reveal that HTLV p24 is chemically distinct from p30-p24 of other animal retroviruses, in agreement with the earlier immunological analyses. However, HTLV p24 shares the common NH(2)-terminal proline and COOH-terminal leucine of all mammalian type C viral p30s. In addition, like bovine leukemia virus (BLV), HTLV lacks the common prolylleucylarginine tripeptide and the larger conserved region found near the NH(2) terminus of the other mammalian type C viral p30s. Alignment of the amino acid sequence of HTLV p24 with previously determined sequences of other retrovirus proteins, including BLV p24, reveals statistically significant sequence homology only to BLV. The results reported here demonstrate that HTLV p24 is related to but chemically distinct from the major core protein of other retroviruses. Similarly, previous results showed that there was no immunological crossreactivity of the p24 protein and reverse transcriptase of HTLV with other retroviruses, including BLV, and no nucleic acid sequence homology. However, the present results, combined with the common size of the p24 and reverse transcriptase, suggest that HTLV may be closer to BLV than any other known retrovirus.
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PMID:Primary structure analysis of the major internal protein p24 of human type C T-cell leukemia virus. 628 Jan 75

Two revertants of ts110 Moloney murine sarcoma virus (MuSV) with wild-type MuSV phenotype were examined for the presence of mos gene products, ts110 MuSV has a temperature-sensitive defect in a function required to maintain the transformed phenotype. The nonproducer 6m2 cell clone transformed by ts110 produces an 85,000-Da gag-mos protein (P85gag-mos) and a 58,000-Da gag protein (P58gag). A spontaneous revertant (clone 54-5A4) of the 6m2 cell clone produces a 100,000-Da protein (P100) recognized by antisera raised against murine leukemia virus p15, p12, and p30 but lacks determinants of p10, reverse transcriptase, and gp70. P100 was specifically recognized by antisera (anti-C3) prepared against a synthetic peptide representing the predicted C-terminal 12 amino acids of Moloney MuSV v-mos gene. Normal sera or anti-C3 blocked with excess synthetic peptide did not recognize P100. Thus, P100 is a product of the gag and mos genes. P100 was found to be phosphorylated. A second wild-type revertant (clone 204-3) was obtained by superinfection of ts110 nonproducer cells with Simian sarcoma associated virus (SSAV); it was also found to contain a phosphorylated P100gag-mos protein. The 204-3 cell clone also contained two gag polyproteins (Pr60gag and Pr55gag) of the size and antigenic properties of those found in SSAV-infected cells. These results provide two examples of P100 gag-mos proteins both derived from the P85gag-mos producing 6m2 cell clone. The P100 gag-mos polyproteins are made in amounts that are easily detected by radiolabeling experiments using [3H]leucine. The intracellular viral RNAs present in 6m2 cells and the two revertant clones were also examined. All three cell clones contained a 4.0 kb RNA hybridizing to v-mos sequences but only the 6m2 clone contained a 3.5 kb mos-containing RNA. Our findings indicate that the 3.5 kb RNA codes for P85gag-mos in cell-free translation experiments (Junghans et al., 1982, J. Mol. Biol. 161, 229). These findings as they relate to the mechanism that produces P100gag-mos instead of P85gag-mos are discussed.
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PMID:Gag-mos Polyproteins encoded by variants of the Moloney strain of mouse sarcoma virus. 630 90

A cell line, TBSV7, that produces noninfectious murine sarcoma virus (MuSV) in the absence of helper MuLV was isolated from TB cells infected with the supernatant of MuSV349 cells. These noninfectious MuSV particles with "immature" C-type virus morphology contain a 2.2 X 10(6)-Da genomic RNA and an uncleaved 62,000-Da gag precursor protein (Pr62). Neither viral envelope proteins (gp70, p15E, p12E) nor reverse transcriptase were detected in these virus particles. Pr62 was found to be phosphorylated in vivo and it could be phosphorylated in vitro with [gamma-32P]ATP, indicating that protein kinase was packaged in these noninfectious virions. In vitro processing of Pr62 to smaller molecular weight proteins could be achieved by the addition of Mo-MuLV and Nonidet P-40. The initial cleavage products were proteins with molecular weights of 38K (Pr38) and 27K (Pr27). Under optimum conditions Pr38 was cleaved to p30 and a protein band migrating with MuLV-p10, while Pr27 was cleaved to a 17,000-Da protein that migrated slower than MuLV-p15 and a protein band migrating with MuLV-p12. Pulse-chase experiments performed on TBSV7 cells superinfected with Mo-MuLV indicated that intracellular processing of Pr62 was much slower than that of Pr65. Cleavage protein products of Pr62 similar in size to the in vitro protein products were also detected in TBSV7 cells superinfected with MuLV.
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PMID:Isolation and characterization of a Mo-MuSV-transformed TB cell line that produces noninfectious MuSV particles with uncleaved gag protein which is processed in the presence of Mo-MuLV. 632 21

The nucleotide sequence of the gag gene of feline leukemia virus and its flanking sequences were determined and compared with the corresponding sequences of two strains of feline sarcoma virus and with that of the Moloney strain of murine leukemia virus. A high degree of nucleotide sequence homology between the feline leukemia virus and murine leukemia virus gag genes was observed, suggesting that retroviruses of domestic cats and laboratory mice have a common, proximal evolutionary progenitor. The predicted structure of the complete feline leukemia virus gag gene precursor suggests that the translation of nonglycosylated and glycosylated gag gene polypeptides is initiated at two different AUG codons. These initiator codons fall in the same reading frame and are separated by a 222-base-pair segment which encodes an amino terminal signal peptide. The nucleotide sequence predicts the order of amino acids in each of the individual gag-coded proteins (p15, p12, p30, p10), all of which derive from the gag gene precursor. Stable stem-and-loop secondary structures are proposed for two regions of viral RNA. The first falls within sequences at the 5' end of the viral genome, together with adjacent palindromic sequences which may play a role in dimer linkage of RNA subunits. The second includes coding sequences at the gag-pol junction and is proposed to be involved in translation of the pol gene product. Sequence analysis of the latter region shows that the gag and pol genes are translated in different reading frames. Classical consensus splice donor and acceptor sequences could not be localized to regions which would permit synthesis of the expected gag-pol precursor protein. Alternatively, we suggest that the pol gene product (RNA-dependent DNA polymerase) could be translated by a frameshift suppressing mechanism which could involve cleavage modification of stems and loops in a manner similar to that observed in tRNA processing.
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PMID:Nucleotide sequence of the gag gene and gag-pol junction of feline leukemia virus. 632 19

p30-related proteins were examined in three in vitro--passaged Gross virus--induced cell lines derived from mice congenic at the H-2 complex: BALB.K-gv-1 (H-2k) (BkGV1), which produces infectious, oncogenic virus, and BALB.B-gv-1 (H-2b) (BbGV1) and BALB/c-gv-1 (H-2d) (BdGV1), which stopped producing infectious virus early in their passage history. The producer BkGV1 line made p30 and its expected precursors. BbGV1 and BdGV1 cells had multiple changes in p30-related protein expression. BbGV1 cells (i) synthesized a truncated gag precursor polyprotein of ca. 47 kilodaltons, (ii) expressed fewer p30-related molecules per cell on their surface than BkGV1 cells, (iii) produced functional reverse transcriptase, and (iv) budded morphologically mature virions which were neither infectious nor oncogenic. BdGV1 cells (i) produced no p30 but expressed some high-molecular-weight proteins with p30 determinants, (ii) expressed fewer p30-related determinants on their surface than BbGV1 cells, and (iii) harbored immature intracisternal viral particles (type A) but did not exhibit budding virions.
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PMID:Variation in p30-related proteins in gross virus-induced tumor cell lines derived from H-2 congenic mice. 660 15

Human immunodeficiency virus type-1 (HIV-1) reverse transcriptase (RT) and its domain fragments were used to map nucleic acid binding sites within the enzyme. Discrete domain fragments were produced after the digestion of three forms of RT (p66, p66/p51 heterodimer, and p51) with V8 protease or trypsin, and the primary structure of each domain fragment was mapped by both immunoblotting and N-terminal amino acid sequence analysis. These domain fragments represent N-terminal, middle, or C-terminal regions of RT. Using Northwestern or Southwestern blotting assays, the domain fragments were evaluated for nucleic acid binding. In this technique, RT proteins are electroblotted onto the membrane and renatured after SDS-PAGE; the proteins are then probed with the primer analogues 32P-labeled d(T)16 or 32P-labeled tRNA(Lys,3). A V8 protease domain fragment spanning residues 195 to approximately 300 (p12), which was found earlier to be UV cross-linked to the primer in intact RT [Sobol et al. (1991) Biochemistry 30, 10623-10631], showed binding to both nucleic acid probes. We first localized nucleic acid binding in p66 to an N-terminal domain fragment of residues 1 approximately equal to 300. By contrast, a C-terminal domain fragment termed p30(303 approximately equal to 560) did not show nucleic acid binding. To investigate the role of the region just N-terminal to residue 303, an expression vector named pRC-35 encoding residues 273-560 was constructed.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mapping of nucleic acid binding in proteolytic domains of HIV-1 reverse transcriptase. 768 75

The identification of Ewing's sarcoma (ES) and peripheral neuroectodermal tumor (PNET) among other small round cell tumors (SRCTs) is a critical issue in musculoskeletal pathology because of the lack of clearly distinctive morphological features. In this study, the authors have compared advantages and limits of two procedures that were recently suggested as additional tools for the identification of ES/PNET, the analysis of p30/32MIC2 antigen by immunohistochemistry, and the evaluation of the fusion products of two specific chromosomal aberrations, the t(11;22)(q24;q12) and the t(21;22)(q22;q12), by reverse transcriptase-polymerase chain reaction (RT-PCR). The authors have analyzed the expression of p30/32MIC2 in 28 cell lines and in 90 tumor samples. p30/32MIC2 was highly expressed in ES/PNET but was also present in all the other cell types. The broad spectrum of positivity for p30/32MIC2 in SRCTs of bone was substantially confirmed by the analysis of tissue samples. In the same material, the authors have evaluated the presence of t(11;22) or t(21;22) transcripts (EWS/FLI-1 and EWS/ERG, respectively) by RT-PCR. These transcripts were found in all the cell lines and tissue samples of ES/PNET, but not in other tumors. The authors' results question the use of p30/32MIC2 immunostaining alone for the identification of ES/PNET and suggest the adoption of RT-PCR as an advantageous alternative. Molecular diagnosis of ES/PNET by RT-PCR is highly specific and can be applied to small amounts of tissue. Moreover, RNA extracted from paraffin-embedded specimens was shown to be suitable for RT-PCR analysis, thus enabling analysis of archival material.
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PMID:Immunostaining of the p30/32MIC2 antigen and molecular detection of EWS rearrangements for the diagnosis of Ewing's sarcoma and peripheral neuroectodermal tumor. 861 85

We report two patients with renal primitive neuroectodermal tumor (PNET) in whom the diagnosis was established by both a cytogenetic and a molecular analysis. Histologically, both renal tumors were composed of uniform immature round cells with a positive immunoreactivity for O13 (p30/32 MIC2). The cytogenetic analysis with in situ hybridization (chromosome painting) demonstrated reciprocal translocation t(11;22)(q24;q12) specific to PNET in the cultured cells derived from each tumor. The reverse transcriptase-polymerase chain reaction (RT-PCR) in both tumors demonstrated EWS/ FLI-1 fusion transcripts, representing the molecular equivalent of t(11;22). A Southern blot analysis also confirmed EWS gene rearrangement in both renal tumors. In addition, the authors also established two new cell lines (designated as FU-RPNT-1 and FU-RPNT-2) from renal PNETs. When transplanted into athymic mice, FU-RPNT-1 and FU-RPNT-2 reproduced and maintained the morphologic and molecular characteristics of the original tumors. In conclusion, the detection of t(11;22) and EWS/FLI-1 fusion transcripts is considered to provide a novel adjunctive method for diagnosing renal PNET. These newly established cell lines thus may be used to investigate the biologic behavior related to renal PNETs.
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PMID:Renal primitive neuroectodermal tumor: a morphologic, cytogenetic, and molecular analysis with the establishment of two cultured cell lines. 955 90

This report describes a feline calicivirus (FCV) p30 gene-based real-time SYBR Green I reverse transcriptase polymerase chain reaction (RT-PCR) assay that is capable of detecting low virus concentrations and a broad range of FCV isolates. The assay consisted of a 1-step RT-PCR reaction with primers delineating a 126-base-pair (bp) region of the FCV p30 gene. Sensitivity of the RT-PCR assay was determined to be equivalent to a FCV titer of 1.2 x 10(1) to 1.2 x 10(2) TCID50/mL. The assay was linear over a wide range of template concentrations and had a reaction efficiency of 95%. Specific FCV amplification products were detected from 51 wild-type FCV isolates, whereas specific products were not detected from a canine calicivirus, a rabbit calicivirus, and a bovine calicivirus. The primers used in this study amplified a large number of North American FCV isolates and further confirm the diagnostic utility of p30 gene-based real-time RT-PCR for detection of FCV.
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PMID:Evaluation of a p30 gene-based real-time reverse transcriptase polymerase chain reaction assay for detection of feline caliciviruses. 1476 47


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