The SH2-SH2-SH3 domain of phospholipase C-gamma 1 directly binds to translational elongation factor-1 alpha

Phospholipase C-gamma 1 (PLC-gamma 1) is a lipase that hydrolyzes PIP2 to g enerate two second messengers, IP3 and DAG, By using the yeast two-hybrid s ystem, we identified the translational elongation factor-1 alpha (EF-1 alph a) as a binding protein of PLC-gamma 1 from the human B-lymphocyte library, Direct interaction between EF-1 alpha and PLC-gamma 1 was confirmed by the in vitro binding experiment using purified PLC-gamma 1, Furthermore, from the in vitro binding experiment, we could demonstrate that the carboxyl ter minal region of EF-1 alpha is involved in the interaction with PLC-gamma 1, and that both SH2 and SH3 domains of PLC-gamma 1 are required for the inte raction with EF-1 alpha. In vivo interaction between EF-1 alpha and PLC-gam ma 1 was confirmed by the immunoprecipitation experiment using anti-EF-1 al pha antibody. The interaction between EF-1 alpha and PLC-gamma 1 was enhanc ed by EGF-treatment, Taken together, we suggest that EF-1 alpha might play a role in PLC-gamma 1-mediated signal transduction.