Comparative analysis of IL-2 and IL-3 induced tyrosine phosphorylation

IL2 and IL3 are polypeptide growth factors that support the survival and proliferation of, respectively, activated T lymphocytes and a range of myeloid cell types. We have examined the involvement of tyrosine phosphorylation in IL2 and IL3 mediated signal transduction. Phosphotyrosyl proteins were immunoaffinity purified and analyzed by single and two dimensional gel electrophoresis. The majority of phosphotyrosyl proteins purified from human T lymphocytes and murine myeloid cells had identical 2 D electrophoretic mobilities, suggesting a high degree of evolutionary conservation. Several proteins in both cell types increased in tyrosine phosphorylation after factor stimulation, including pp200, pp180, pp92, and pp42. The 92 kD protein was the most highly modulated phosphoprotein identified, with increases in phosphorylation greater than 18 fold after 20 min of stimulation. These results suggest that signal transduction pathways for IL2 and IL3 involve tyrosine phosphorylation of protein substrates common to both lymphoid and myeloid linages.