Cloning and expression of a cDNA encoding a catalytically active fragment of calf thymus DNA polymerase alpha

A calf thymus cDNA expression library was constructed in the Eco RI site of λgtll and probed with an antibody raised against calf thymus DNA polymerase α. Three classes of antibody-reactive clones were isolated. The largest class carried a 1.9 kilobase calf cDNA insert and expressed a 165–175 kilodalton β-galactosidase:calf fusion protein which displayed DNA polymerase activity. The characteristic responses of the polymerase activity to alpha-specific inhibitors and antibodies identified the 1.9 kilobase cDNA as a sequence specifically derived from the structural gene encoding the pol α catalytic core.