Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 32,000-dalton protein (p32) located in avian retrovirus cores was immunoprecipitated from [35S]methionine-labeled avian myeloblastosis virus (AMV) propagated in cultured chicken embryo fibroblast cells by an antiserum preparation (sarc III) derived from tumor-bearing hamsters injected with cloned and passaged cells from an avian sarcoma virus-induced primary hamster tumor. Since sarc III serum apparently contained antibodies only to virus-coded proteins and not to chicken cellular proteins, the immunoprecipitation of p32 from AMV by sarc III serum strongly suggested that p32 is virus coded. The origin of p32 was more definitively established by demonstrating the existence of a structural relationship between p32 and the AMV DNA polymerase. AMV p32 cross-reacted with the beta polypeptide of AMV alphabeta DNA polymerase in radioimmunoprecipitation and radioimmunoprecipitation inhibition assays, indicating that p32 and beta share common antigenic determinants. This relationship was clarified by sodium do-decyl sulfate-polyacrylamide gel electrophoretic analysis of the peptides generated by limited proteolysis of 125I-labeled AMV DNA polymerase polypeptides and of 125I-labeled AMV p32 by chymotrypsin or Staphylococcus aureus V-8 protease. The peptides which appeared during proteolytic digestion of p32 were a subset of those produced by digestion of the beta polypeptide; however, p32 had no discernible peptides in common with the alpha polypeptide. Further, all of the peptides produced by limited proteolysis of beta were present in the digests of either p32 or alpha. Our findings suggest that p32 is apparently derived by cleavage of the beta polypeptide of AMV DNA polymerase, presumably at a site near or identical to that at which alpha is generated from beta by proteolytic cleavage.
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PMID:Virus-coded origin of a 32,000-dalton protein from avian retrovirus cores: structural relatedness of p32 and the beta polypeptide of the avian retrovirus DNA polymerase. 8 16

Analogues of dUTP bearing a photoreactive 2-nitro-5-azidobenzoyl (NAB) group linked via spacers of varying length (n = 2, 4, 7-13 atoms) to the 5-position of the uridine ring (NAB-n-dUTP) were synthesized and characterized. DNA polymerase beta efficiently incorporated these analogues into synthetic primer-template substrates in place of TTP, which allowed us to selectively introduce a photoreactive group at the 3' primer terminus. After completing photoreactive primer synthesis, the reaction mixtures were irradiated with monochromatic UV light (315 nm) in the presence of human replication protein A (RPA), a heterotrimer consisting of three subunits with molecular mass 70 kDa (p70), 32 kDa (p32), and 14 kDa (p14), and were separated by SDS-PAGE. The photoreactive primers cross-linked directly with p70 and p32, but cross-linking of p14 was not achieved even by varying the length of the spacer group. The data speak in favor of the protection of p14 by other RPA subunits from the interaction with 3'-end of the primer. Cross-linking of substrates to pol beta is inhibited when the analogue bears a short spacer (n = 2, 4, 7, and 8), but this is abrogated somewhat when longer spacers (n = 9-13) are examined. On the basis of these observations, we suggest that RPA and pol beta form a complex on primer-template substrates.
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PMID:Synthesis of base-substituted dUTP analogues carrying a photoreactive group and their application to study human replication protein A. 1089 64