In vitro proteolytic cleavage of Gazdar murine sarcoma virus p65gag.

Moloney murine leukemia virus, disrupted in concentrations of 0.1 to 0.5% Nonidet P-40, catalyzed the cleavage of p65, the gag gene polyprotein of the Gazdar strain of murine sarcoma virus, into polypeptides with sizes and antigenic determinants of murine leukemia virus-specified p30, p15, pp12, and p10. Cleavage performed in the presence of 0.15% Nonidet P-40 in water yielded polypeptides of approximately 40,000 (P40) and 25,000 (P25) Mr. In vitro cleavage performed in a buffered solution containing dithiothreitol in addition to 0.1% Nonidet P-40 allowed the efficient processing of P40 to p30 and a band migrating with p10. Immunoprecipitation with monospecific sera indicated that P40 contained p30 and p10, whereas P25 contained p15 and pp12 determinants. P40 and P25 are similar in size and antigenic properties to Pr40gag and Pr25gag observed in infected cells (Naso et al, J. Virol. 32:187-198, 1979).