Differences in intracellular location of pp60src in rat and chicken cells transformed by Rous sarcoma virus

We have investigated the intracellular location of pp60src in Rous sarcoma virus-transformed rat cells (RR1022) by indirect immunofluorescence microscopy and cell fractionation. Immunofluorescence data suggest that pp60src is predominantly associated with the nuclear envelope and the juxtanuclear reticular membrane structures. The bulk of pp60src and of the associated phosphotransferase activity fractionated with nuclei and not with plasma membranes in disrupted cells. This localization contrasts strikingly with the association of pp60src with the plasma membrane of Rous sarcoma virus-transformed chicken fibroblasts. We propose that pp60src is a membrane protein that associates with cellular membranes through hydrophobic regions and that this membrane association is a general feature of the interaction of pp60src with avian and mammalian cells. Although there are major differences in the intracellular localizations of pp60src, it may interact with cellular membranes through one or more NH2-terminal hydrophobic regions.