ABSTRACT
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.
Subject(s)
Animals , Adaptor Proteins, Signal Transducing , Amino Acid Sequence , COS Cells/enzymology , Chlorocebus aethiops , Enzyme Activation , Epidermal Growth Factor/pharmacology , Immunoprecipitation , Inositol 1,4,5-Trisphosphate/metabolism , Molecular Sequence Data , Type C Phospholipases/chemistry , Phosphoric Monoester Hydrolases/chemistry , Protein Binding , Signal Transduction , src Homology Domains/physiologyABSTRACT
Thermoactinomycetes vulgaris is a thermophilic actinomycetes growing optimally at 50 degrees C and Streptomyces albus, S. coelicolor, S. fasciculus and S. olivochromogenes are thermophilically disposed transition species of actinomycetes, which have optimum biomass at 40 degrees C. The acid/alkaline phosphatase and acid/alkaline/neutral protease enzyme from Streptomycetes species showed enzyme activity up to 90 degrees C. In comparison to phosphatases and proteases from T. vulgaris it was concluded that these thermophilically disposed transition species showed macromolecular thermostability i.e. thermostable enzymes and protein.