Two-dimensional Analysis of Interleukin 2-Regulated Tyrosine Kinase Activation Mediated by the p70-75 β Subunit of the Interleukin 2 Receptor

The proliferation of activated T lymphocytes is dependent on the interaction of the polypeptide growth factor interleukin 2 (IL 2) with its heterodimeric receptor, which consists of a p55 alpha subunit and a p70-75 beta subunit. Previously, it was shown that IL 2 stimulates rapid serine phosphorylation of several membrane and cytysolic proteins. Here, using anti-phosphotyrosine antibodies to purify phosphotyrosyl proteins and two-dimensional gel analysis, we show that IL 2 stimulates rapid tyrosine phosphorylation of a variety of cellular proteins, including pp180, pp92, and pp42 in activated human T lymphocytes. In addition, we have examined IL 2-induced tyrosine phosphorylation in the human cell line YT2C2 which expresses mostly the beta subunit of the IL 2 receptor and the gibbon cell line MLA-144 which expresses only the beta subunit. In both of these cell lines, IL 2 induced tyrosine phosphorylation of the same proteins phosphorylated in normal human T lymphocytes in response to IL 2. We conclude that the beta subunit is sufficient to induce tyrosine phosphorylation of the normal cellular target substrates involved in signal transduction.