Isolation and partial characterization of the poly(A) polymerases from HeLa cells infected with vaccinia virus.

Three poly(A) polymerases were isolated from HeLa cells infected with vaccinia virus.Two were cellular enzymes.The first was a poly(A) polymerase that was located primarily in the nucleus, comprised a single polypeptide with a M, = 50,000, was stimulated by Mn2+ and also by Mg'+, and was able to use RNA, but not oligo(A), as primer.The second, which accounted for about 75% of the total cellular poly(A) polymerase activity, was located primarily in the cytoplasm, consisted of a single polypeptide with a M, = 75,000, was absolutely dependent on the presence of Mn2+, and was able to use both RNA and oligo(A) as primer.The third enzyme was present only in cells infected with vaccinia virus.It was a heterodimer composed of two polypeptides with M, = 57,000 and 37,000, was stimulated by Mn2+ and also by Mg'+, and was able to use both RNA and oligo(A) as primer.It was identical in all properties tested with the poly(A) polymerase that can be isolated from vaccinia virus cores except for somewhat different chromatographic properties, caused possibly by a charge difference.The subunits of this vaccinia virus-specified poly(A) polymerase were different not only from those of either of the two host cell poly(A) polymerases, but also from those of the vaccinia virus-specified DNA-dependent RNA polymerase; it is therefore a distinct virus-specified enzyme.No other virus-specified poly(A) polymerase was present in infected cells.