On the Binding of DNA Polymerase Alpha to Nuclear Structure in Mouse Myeloma MOPC104E

Abstract

DNA polymerase EC-2.7.7.7 .alpha. of mouse myeloma MOPC104E cells was resolved into at least 3 active types which were designated forms A, B and C in order of elution from DEAE cellulose column. Of total DNA polymerase .alpha. activity of mouse myeloma MOPC104E cells, 84% was localized in nuclei isolated using Ca2+-containing medium. Forty percent of total nuclear activity was released upon treatment with salt-free medium, and most of the remaining activity was extracted with media containing 0.15 or 0.3 M KCl. The major species of 0 M KCl extracts was form C of DNA polymerase .alpha., while the activity in 0.15 M KCl extract was mainly composed of form B. The KCl concentration required for extraction of form B from the nuclei seemed to coincide with that required for the elution of DNA polymerase .alpha. from native DNA cellulose column. These observations suggested that form B was in the complex with DNA or chromatin structure in nucleus whereas form C was free from the structure.