Vinculin and 36 kDa protein are not tyrosine-phosphorylated in Rous sarcoma virus infected cells which have been treated with interferon.

The expression of membrane-associated transformation-specific parameters was analyzed in de novo Rous sarcoma virus (strain SR-RSV-D) infected chicken embryo fibroblasts pretreated with homologous interferon. Cellular morphology, hexose transport, microfilament organization, and tyrosine-phosphate content of two primary substrates of the transformation-generating viral kinase, pp60src, were found indistinguishable from non-infected controls. These observations support the hypothesis that vinculin and possibly 36 kDa protein are involved in microfilament organization and that tyrosine-phosphorylation of these structural proteins is a prerequisite for the rearrangement of microfilaments during transformation. In de novo infection, interferon pretreatment reduces viral protein synthesis and pp60src activity as compared to non-treated, SR-RSV-D infected cells. However, the phosphotyrosine content of total cellular proteins as measured under steady state conditions is as high in interferon-pretreated as in nontreated transformed cells.