Interaction of phosphatidylinositol-4-monophosphate with a low activity form of dna polymerase alpha: a potential mechanism for enzyme activation

Abstract

1. 1. DNA polymerase alpha isolated from Norman murine myxosarcoma exhibited two isozyme forms, one with low specific activity and low DNA binding affinity (a 1), and one with high specific activity and high DNA binding affinity (A 2). 2. 2. DNA polymerase alpha a 1, but not A 2, showed a significant increase in specific activity after treatment with phosphatidylinositol, ATP and phosphatidylinositol kinase, or with phosphatidylinositol-4-monophosphate. 3. 3. Treatment of DNA polymerase alpha a 1 with the phospholipase C hydrolysis product of phosphatidylinositol-4-monophosphate, inositol-1,4-bisphosphate, was sufficient to effect the transient increase in activity of polymerase a 1 to a form not chromatographically distinguishable from isozyme form A 2