The SH2-SH2-SH3 domain of phospholipase C-γ1 directly binds to translational elongation factor-1α

Phospholipase C-γ1 (PLC-γ1) is a lipase that hydrolyzes PIP₂ to generate two second messengers, IP₃ and DAG. By using the yeast two-hybrid system, we identified the translational elongation factor-1α (EF-1α) as a binding protein of PLC-γ1 from the human B-lymphocyte library. Direct interaction between EF-1α and PLC-γ1 was confirmed by the in vitro binding experiment using purified PLC-γ1. Furthermore, from the in vitro binding experiment, we could demonstrate that the carboxyl terminal region of EF-1α is involved in the interaction with PLC-γ1, and that both SH2 and SH3 domains of PLC-γ1 are required for the interaction with EF-1α. In vivo interaction between EF-1α and PLC-γ1 was confirmed by the immunoprecipitation experiment using anti-EF-1α antibody. The interaction between EF-1α and PLC-γ1 was enhanced by EGF-treatment. Taken together, we suggest that EF-1α might play a role in PLC-γ1-mediated signal transduction.