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Activation of SV40 DNA replication in vitro by cellular protein phosphatase 2A.
Author(s) -
Virshup D.M.,
Kauffman M.G.,
Kelly T.J.
Publication year - 1989
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1989.tb08568.x
Subject(s) - dna replication , biology , associate editor , dna , microbiology and biotechnology , library science , genetics , computer science
We have made use of the cell‐free SV40 DNA replication system to identify and characterize cellular proteins required for efficient DNA synthesis. One such protein, replication protein C (RP‐C), was shown to be involved with SV40 large T antigen in the early stages of viral DNA replication in vitro. We demonstrate here that RP‐C is identical to the catalytic subunit of cellular protein phosphatase 2A (PP2Ac). The purified protein dephosphorylates specific phosphoamino acid residues in T antigen, consistent with the hypothesis that SV40 DNA replication is regulated by modulating the phosphorylation state of the viral initiator protein. We also show that purified RP‐C/PP2Ac preferentially stimulates SV40 DNA replication in extracts from early G1 phase cells. This finding suggests that the activity of a cellular factor that influences the net phosphorylation state of T antigen is cell cycle dependent.