Effect of RNA tumor virus-specific protein p30 on reverse transcriptase. Intraspecies and interspecies interaction...

Reverse transcriptase and p30 were purified from various retroviruses and the intra- and interspecific interaction between the two proteins were studied. The intraspecific complex stimulates [3H]TMP incorporation into (dT)12.(rA)n severalfold above that of the enzyme itself whereas DNA synthesis in the presence of the interspecific complex can stimulate DNA synthesis about 1.5-fold. The sedimentation rate value of the intraspecies complex varies between 12 and 16 S with an estimated molecular weight of 400,000. The molar ratio of p30:reverse transcriptase within the complex is 8:1. Both complexes can be dissociated into their original protein components by exposure to salt (kcl) solution, except that 0.3 M KCl will dissociate the interspecies complex whereas 0.8 M KCl is required for dissociation of the intraspecies complex. Competition studies in which an interspecies complex was exposed to p30 autologous to reverse transcriptase within the complex resulted in the displacement of the heterologous (p30) protein and the formation of a new intraspecific complex.