STOICHIOMETRY OF CELLULAR AND VIRAL COMPONENTS IN THE POLYOMAVIRUS MIDDLE-T ANTIGEN TYROSINE KINASE COMPLEX

Our results indicate that only one type of tyrosine kinase is present within each middle-T antigen-tyrosine kinase complex, suggesting that middle-T antigen forms separate complexes with different tyrosine kinases. Furthermore, we determined that there is only one molecule of middle-T antigen within any one of these complexes. We interpret this to mean that in any given cell, polyomavirus transformation involves, at least in part, the simultaneous deregulation of a number of separate pathways controlling cellular proliferation. Finally, we also demonstrate that the separate middle-T:pp60(c-src) and middle-T:pp59(c-fyn) complexes are each able to interact with the same cellular p81/85-kDa phosphoprotein, a possible component of the phosphatidyl-inositol kinase.