Temperature-sensitive transformation by Rous sarcoma virus and temperature-sensitive protein kinase activity (original) (raw)

The transforming protein of Rous sarcoma virus, p60src, has associated with it a protein kinase activity. We examined whether a correlation exists between the cellular concentration of enzymatically active p60src and the degree to which chick cells are transformed by mutants of Rous sarcoma virus which are temperature-sensitive for transformation. Such a correlation does exist, but cells infected with some mutants could be shown to contain, at the nonpermissive temperature, an amount of protein kinase activity equal to 30 to 40% of that in a wild-type transformed cell. We quantified the amount of virus-induced protein kinase activity by precipitation of p60src with an excess of antitumor antiserum. Our initial measurements of activity were serious underestimates, due to the lability of the protein kinase activity associated with p60src of at least four temperature-sensitive mutants. In fact, no activity at all was associated with p60src of tsLA90 when immunoprecipitation was perform...