Replication Protein A1 (RPA1)

Replication protein A (RPA) is a 3-subunit single-stranded DNA (ssDNA)-binding protein that has been isolated from human cells and found to be essential for in vitro replication of the papovavirus SV40. The human cDNA directed production in E. coli of a 70-kD protein that reacted with a monoclonal antibody directed against the 70-kD subunit of the human protein. The recombinant subunit, purified from bacteria, exhibited single-stranded DNA-binding activity comparable to that of the complete RPA complex. It could substitute for the complete complex in stimulating the activity of DNA polymerase alpha-primase, but could not substitute for the complete complex in SV40 DNA replication in vitro, suggesting an important functional role for the other subunits.