Insulin receptor autophosphorylation and exogenous substrate phosphorylation: role of receptor C-terminus and effects of mild reduction.
A mutant insulin receptor lacking the final 69 amino acids of the beta-subunit (delta 69) was used to examine the role of the receptor C-terminal domain in kinase activation. With increasing deletion of the C-terminus from 43 to 69 amino acids we show that exogenous peptide kinase activity is lost before autokinase activity. Despite this, phosphorylation of an in vivo insulin receptor substrate, IRS-1, and insulin bioeffects are similar to wild-type. In addition, with the exception of insulin-stimulated peptide phosphorylation, the reductant glutathione modified kinase activity in a similar manner for both wild-type and mutant delta 69 receptors. These results suggest that conformational changes proposed to occur within the receptor C-terminus upon insulin binding may not be necessary for kinase activation under a variety of conditions.
Clark
S
S
University of Melbourne, Department of Medicine, Royal Melbourne Hospital, Victoria, Australia.
Konstantopoulos
N
N
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011487:Protein Conformation; D011972:Receptor, Insulin / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D017384:Sequence Deletion; D013379:Substrate Specificity; D014162:Transfection
C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D009842:Oligopeptides; D010750:Phosphoproteins; D011972:Receptor, Insulin