Three forms of the RNA dependent DNA polymerase were isolated from highly purified avian sarcoma virus B77 grown in duck embryo fibroblasts, using sequential chromatography on DEAE cellulose, phosphocellulose, and poly(U) cellulose. One form, which sedimented with about 5.2S, contained only one species of polypeptides, with a molecular weight of 63,000; a second sedimented with about 7.8 S and contained only one species of polypeptide with a molecular weight of 81,000; and a third form, which sedimented with about 7.3 S, contained 2 species of polypeptides with molecular weights of 63,000 and 81,000. The molecular constitution of the 3 enzyme forms were therefore α, β2, and αβ. All 3 possessed almost the same specific activity with poly(rA).oligo(dT) as the primer template. Forms α and αβ of avian sarcoma virus DNA polymerase have already been described in the literature; form β2 is a new form. All 3 forms possessed ribonuclease H activity, the relative specific activities of the α, β2, and αβ forms being about 1:4:5. All 3 enzyme forms were inhibited by antiserum to the αβ form, but whereas the α and αβ forms could be inhibited by about 95%, the maximum degree of inhibition of the β2 form was about 80%. The three enzyme forms also differed with respect to heat stability at 46°, the monomeric α form of the enzyme being only about one half as stable as the two dimeric forms.
|Number of pages||9|
|Journal||Journal of Biological Chemistry|
|State||Published - 1977|