Interaction of DNA polymerase alpha-primase with cellular replication protein A and SV40 T antigen

The purified human single-stranded DNA binding protein, replication protein A (RP-A), forms specific complexes with purified SV40 large T antigen and with purified DNA polymerase alpha-primase, as shown by ELISA and a modified immunoblotting technique. RP-A associated efficiently with the isolated primase, as well as with intact polymerase alpha-primase. The 70 kDa subunit of RP-A was sufficient for association with polymerase alpha-primase. Purified SV40 large T antigen bound to intact RP-A and to polymerase-primase, but not to any of the separated subunits of RP-A or to the isolated primase. These results suggest that the specific protein-protein interactions between RP-A, polymerase-primase and T antigen may play a role in the initiating of SV40 DNA replication.