A novel DNA polymerase activity found in association with intracisternal A-type particles

A DNA polymerase activity that promotes the synthesis of poly(dT) has been found in association with intracisternal A-type particles isolated from several mouse tumors. The poly(dT) synthesis activity requires a DNA or RNA primer, is optimal at high salt concentration, prefers magnesium over manganese, and is stimulated by poly(rA). No significant incorporation of dAMP, dGMP, or dCMP was detected in the presence of several RNA and DNA template-primers. The enzyme activity differs in several of its properties from the poly(rA)-directed DNA polymerase activity associated with Rauscher murine leukemia virus.