Elongation of primed DNA templates by eukaryotic DNA polymerases.

Abstract
The combined action of DNA polymerase .alpha. and DNA polymerase .beta. [from human cervical carcinoma HeLa cells] leads to the synthesis of full-length linear DNA strands with [phage] .phi. X174 DNA templates containing an RNA primer. The reaction can be carried out in 2 stages. In the 1st stage, DNA polymerase .alpha. catalyzes the synthesis of a chain that averaged 230 deoxynucleotides long and was covalently linked to the RNA primer. In the 2nd stage, DNA polymerase .beta. elongates the DNA strand covalently attached to the RNA primer to full length. With DNA primers, DNA polymerase .alpha. catalyzes only limited deoxynucleotide addition whereas DNA polymerase .beta. alone elongates DNA primed templates to full length. DNA polymerase .beta. can also stimulate the synthesis of adenovirus DNA in vitro in the presence of a cytosol extract from adenovirus-infected cells. In all of these systems, dNMP [deoxyribonucleoside monophosphates] incorporation catalyzed by DNA polymerase .beta. was sensitive to N-ethylmaleimide but this polymerase activity was resistant to N-ethylmaleimide with poly(rA) .cntdot. oligo(dT) as the primer template.