A Single-Strand-Specific DNA-Binding Protein from Mouse Cells that Stimulates DNA Polymerase.. Its Modification by Phosphorylation

Abstract

A protein of MW 30,000-35,000 was isolated from mouse Ehrlich ascites tumor cells. This protein binds preferentially to single-stranded DNA. Evidence is presented that this protein maintains single-stranded DNA in an extended configuration. In the presence of single-stranded template the protein stimulates mammalian DNA polymerase .alpha. but not the mammalian DNA polymerase .beta. and not some microbial DNA polymerase [Escherichia coli and T7]. The protein is phosphorylated in vitro by a chromatin-associated protein kinase. The modified DNA-binding protein does not stimulate the DNA polymerase .alpha.