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Chapter 8,887

Insulin receptor autophosphorylation and exogenous substrate phosphorylation: role of receptor C-terminus and effects of mild reduction

Clark, S.; Konstantopoulos, N.

Biochemical and Biophysical Research Communications 200(1): 330-337

1994


ISSN/ISBN: 0006-291X
PMID: 8166701
DOI: 10.1006/bbrc.1994.1452
Accession: 008886923

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.

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