Intranuclear localization of DNA polymerases alpha and beta in regenerating rat liver

Abstract

1. Nuclei isolated from regenerating rat liver were digested with micrococcal nuclease and fractionated on glycerol gradients into soluble chromatin fragments and chromatin associated with the nuclear skeleton. 2. Distributions of DNA polymerases alpha and beta in these fractions were different. While beta polymerase followed closely the distribution of the chromatin fragments, alpha polymerase associated preferentially with the skeleton-chromatin complex. 3. At least 20% of total alpha polymerase in the nuclei was shown to be bound to the skeleton. In nuclei extracted with isotonic sucrose buffer containing 50 or 100 mM Tris-Cl the portion of the skeleton associated enzyme was increased to 40-50%. 4. These data show that the skeleton bound alpha polymerase was preferentially retained in the nuclei during salt extraction. 5. Contrary to the replicational DNA polymerase alpha, DNA polymerase beta did not show any affinity to the skeleton.