Association of polyoma virus middle T antigen and pp60src with cytoskeletal elements

Polyoma virus middle T antigen (mT) as well as pp60v-src, the oncogene product of Rous sarcoma virus, associate with membranes and cytoskeletal structures in virus-infected cells. Furthermore, mT has been shown to be tightly bound to pp60c-src, the cellular homolog of pp60v-src. While the presence of pp60v-src in focal contacts has been demonstrated, the localization of mT and pp60c-src is less clear. We show here that mT is associated with focal contacts and that the phosphorylated protein can be immunoprecipitated with anti-vinculin serum. We suggest that the mT/pp60c-src complex and pp60v-src are tightly bound to vinculin. This interaction may be relevant in the process of cell transformation since disorganization of the actin filament network seems to play an important role in the deregulation of cell growth observed in tumor cells.