FIG. 5.
The inactive C subunit mutants capable of forming complexes with MT and pp60c-src also associate with Shc and PI 3-kinase. Lysates of cell lines expressing the control vector (GREonly) or epitope-tagged wt (wt-36) or mutant C subunits (see Fig. 2 for nomenclature) were immunoprecipitated with 12CA5 antibody. Only those inactive C subunit mutants which retained the ability to bind substantial amounts of pp60c-src were analyzed. The Western blot was sequentially probed with antibodies recognizing the 85-kDa subunit of PI 3-kinase (PI3K), Shc, phosphotyrosine (the phosphotyrosine-containing MT band [P-TYR] is indicated), and MT (PYMT). All lanes shown are from the same experiment and gel, but they were not all originally adjacent. The data shown are representative of results obtained from three independent experiments.