Both Interleukin 4 and Interleukin 13 Induce Tyrosine Phosphorylation of the 140-kDa Subunit of the Interleukin 4 Receptor

We have investigated tyrosine phosphorylation of cellular proteins induced by interleukin (IL) 4 and compared it with the effects of three related cytokines, IL-2, IL-7, and IL-13. We show here that both IL-4 and IL-13 stimulate tyrosine phosphorylation of the 140-kDa IL-4 receptor subunit, which suggests that this receptor protein is used by both cytokines. Receptor phosphorylation induced by IL-13 was both weaker and slower than with IL-4. Stimulation of cells with IL-2 and IL-7 induced identical phosphorylation patterns to each other but not phosphorylation of the 140-kDa IL-4 receptor subunit. The only signal appearing upon stimulation with any of the four cytokines was the weak phosphorylation of an unidentified protein of 160 kDa. SH2 domains of p56lck and p59fyn precipitated the same proteins as anti-phosphotyrosine antibodies after IL-4 stimulation, which suggests that a src-type kinase may be involved in signal transduction through the IL-4 receptor.