Phospholipase C-gamma1, 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-gamma1 regulation is unclear. By peptide-mass fingerprinting analysis, we have identified SHIP1 as the binding protein for the SH3 domain of PLC-gamma1. SHIP1 was co-immunoprecipitated with PLC-gamma1 and potentiated EGF-induced PLC-gamma1 activation. However, inositol 5'-phosphatase activity of SHIP1 was not required for the potentiation of EGF-induced PLC-gamma1 activation. Taken together, these results suggest that SHIP1 may function as an adaptor protein which can potentiate EGF-induced PLC-gamma1 activation without regards to its inositol 5'-phosphatase activity.
Adaptor Proteins, Signal Transducing ; Amino Acid Sequence ; Animals ; COS Cells/enzymology ; Cercopithecus aethiops ; Enzyme Activation ; Epidermal Growth Factor/*pharmacology ; Immunoprecipitation ; Inositol 1,4,5-Trisphosphate/metabolism ; Molecular Sequence Data ; Phospholipase C/chemistry/*metabolism ; Phosphoric Monoester Hydrolases/chemistry/*metabolism ; Protein Binding ; Signal Transduction ; src Homology Domains/*physiology