K. Sato et al., PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE STIMULATES PHOSPHORYLATION OF THE ADAPTER PROTEIN SHC BY C-SRC, FEBS letters, 410(2-3), 1997, pp. 136-140
The adaptor protein She was prepared as glutathione S-transferase fusi
on proteins (GST-Shc) and used as in vitro substrate for c-Src. Since
phosphotyrosine-binding domain of She has been shown to bind phosphati
dyl-inositol 4,5-bisphosphate (PtdIns(4,5)P2) [Zhou et al. (1995) Natu
re 378, 584-592], effect of PtdIns(4,5)P2 on the phosphorylation of GS
T-Shc by c-Src was examined, PtdIns(4,5)P2 stimulated the phosphorylat
ion of GST-Shc without any effect on the c-Src activity as judged by b
oth its autophosphorylation and phosphorylation of exogenous substrate
, Cdc2 peptide. On the other hand, phosphatidylserine, phosphatidic ac
id, phosphatidylinositol, and phosphatidylinositol 4-phosphate but not
phosphatidylcholine stimulated the c-Src activity itself. K-m for GST
-Shc in the presence of 1 mu M PtdIns(4,5)P2 was calculated to be 90 n
M. The PtdIns(4,5)P2-dependent phosphorylation of GST-Shc was inhibite
d by a GST-fusion protein containing the phosphotyrosine-binding domai
n of She. These results suggest that PtdIns(4,5)P2 can act as a regula
tor of phosphorylation of She by c-Src through its binding to She. (C)
1997 Federation of European Biochemical Societies.