An assessment of human insulin receptor phosphorylation and exogenous kinase activity following deletion of 69 residues from the carboxyl-terminus of the receptor beta-subunit.
A mutant human insulin receptor with a carboxyl-terminal deletion of 69 amino acids (proreceptor residues 1287-1355) is expressed as a stable protein in transiently transfected COS cells. We find that in intact cells this mutant is phosphorylated in an insulin-dependent manner on core tyrosines 1158, 1163 and 1163. As expected, the carboxyl-terminal beta-subunit phosphorylation sites (serines 1305/6, tyrosines 1328/34 and threonine 1348) are absent from this mutant. However, the two major insulin-stimulated serine phosphopeptides remain. In intact cells, insulin stimulates exogenous substrate phosphorylation by the truncated receptor only approximately 1.9-fold (cf. approximately 9-fold for the wild-type receptor in these cells), a consequence of a approximately 4.8-fold elevation in basal insulin-independent kinase activity.
Tavaré
J M
JM
Department of Biochemistry, School of Medical Sciences, University of Bristol, UK.
Ramos
P
P
Ellis
L
L
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000276:immunology; D010766:Phosphorylation; D010957:Plasmids; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism*; D011972:Receptor, Insulin / Q000235:genetics* / Q000378:metabolism*; D015183:Restriction Mapping; D017384:Sequence Deletion; D014162:Transfection
D046911:Macromolecular Substances; D009842:Oligopeptides; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin