INTERACTION OF THE IL-2 RECEPTOR WITH THE SRC-FAMILY KINASE-P56LCK - IDENTIFICATION OF NOVEL INTERMOLECULAR ASSOCIATION

In the interleukin-2 (IL-2) system, intracellular signal transduction is triggered by the beta-chain of the IL-2 receptor (IL-2R-beta); however, the responsible signaling mechanism remains unidentified. Evidence for the formation of a stable complex of IL-2R-beta and the lymphocyte-specific protein tyrosine kinase p56lck is presented. Specific association sites were identified in the tyrosine kinase catalytic domain of p56lck and in the cytoplasmic domain of IL-2R-beta. As a result of interaction, IL-2R-beta became phosphorylated in vitro by p56lck. Treatment of T lymphocytes with IL-2 promotes p56lck kinase activity. These data suggest the participation of p56lck as a critical signaling molecule downstream of IL-2R via a novel interaction.