A DNA polymerase alpha-associated 56 kDa protein kinase.

Initiation of chromosomal DNA replication must be carefully regulated during the cell cycle. We report that Drosophila embryo DNA polymerase alpha complex, isolated by immunological techniques, contains a protein kinase activity. The kinase will phosphorylate histone H1, but prefers peptides contained in the DNA polymerase alpha-kinase complex. Renaturation experiments determined that the kinase activity resides in a 56-kDa peptide.