Multisite serine phosphorylation of the insulin and IGF-I receptors in transfected cells.
Serine phosphorylation of insulin/IGF-I receptors in transfected fibroblasts was analysed by peptide mapping. PMA stimulated the phosphorylation of 5 distinct insulin receptor phosphopeptides: a single major phosphothreonine peptide containing Thr-1348, one major and 3 minor phosphoserine peptides. The major insulin-stimulated phosphoserine peptides were the same as those after PMA, with the exception of 2 minor phosphoserine peptides. PMA stimulated phosphorylation of a single major IGF-I receptor phosphoserine peptide which was phosphorylated to a lesser extent after IGF-I. We conclude that insulin/IGF-I and PMA stimulate phosphorylation of the same sites, but differ in the extents of phosphorylation.
Pillay
T S
TS
Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, UK.
Whittaker
J
J
Lammers
R
R
Ullrich
A
A
Siddle
K
K
D000818:Animals; D002460:Cell Line; D005347:Fibroblasts; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D010449:Peptide Mapping; D010766:Phosphorylation / Q000187:drug effects; D011972:Receptor, Insulin / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017451:Receptors, Somatomedin; D012694:Serine / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013912:Threonine / Q000378:metabolism; D014162:Transfection
D007328:Insulin; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013912:Threonine; D012694:Serine; D007334:Insulin-Like Growth Factor I; D011972:Receptor, Insulin; D013755:Tetradecanoylphorbol Acetate