Inositol 5′-phosphatase, SHIP1 interacts with phospholipase C-γ1 and modulates EGF-induced PLC activity

Abstract

Phospholipase C-γ1, containing two SH2 and one SH3 domains which participate in the interaction between signaling molecules, plays a significant role in the growth factor-induced signal transduction. However, the role of the SH domains in the growth factor-induced PLC-γ1 regulation is unclear. By peptide-mass fingerprinting analysis, we have identified SHIP1 as the binding protein for the SH3 domain of PLC-γ1. SHIP1 was co-immunoprecipitated with PLC-γ1 and potentiated EGF-induced PLC-γ1 activation. However, inositol 5′-phosphatase activity of SHIP1 was not required for the potentiation of EGF-induced PLC-γ1 activation. Taken together, these results suggest that SHIP1 may function as an adaptor protein which can potentiate EGF-induced PLC-γ1 activation without regards to its inositol 5′-phosphatase activity.