PURIFICATION OF A DNA-BINDING PROTEIN FROM A MULTI-PROTEIN COMPLEX-ASSOCIATED WITH DNA POLYMERASE-ALPHA IN PEA (PISUM-SATIVUM)

DNA polymerase-alpha in pea exists as a large multiprotein complex. One of the activities exhibited by the complex is DNA-binding. In order to elucidate the function of this activity the polypeptides which exhibit DNA binding have been purified so as to study them individually. Fractionation of the complex by SDS-polyacrylamide gel electrophoresis, followed by blotting and probing with labelled DNA reveals the existence of three polypeptides which have binding activity; these have molecular weights of c. 109, 70 and 42 kDa. Of these, the 42 kDa polypeptide exhibits the greatest DNA-binding activity in the blots. This protein has been purified to homogeneity; during purification its molecular weight declines to c. 36 kDa.