The regulatory role of known tyrosine autophosphorylation sites of the insulin receptor kinase domain. An assessment by replacement with neutral and negatively charged amino acids

Autophosphorylation of the insulin receptor has been previously documented to activate the phosphotransferase activity of the receptor from 20- to 200-fold. Biochemical studies have correlated activation of the receptor kinase with the autophosphorylation of tyrosines residues 1158, 1162, and 1163....

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Bibliographic Details
Published in:The Journal of biological chemistry 1991-01, Vol.266 (2), p.990-996
Main Authors: Zhang, B, Tavaré, J M, Ellis, L, Roth, R A
Format: Article
Language:English
Subjects:
Amino Acids - metabolism
Biological and medical sciences
Blotting, Western
Cell receptors
Cell structures and functions
Cells, Cultured
DNA - genetics
Electrophoresis, Polyacrylamide Gel
Fundamental and applied biological sciences. Psychology
Hormone receptors. Growth factor receptors. Cytokine receptors. Prostaglandin receptors
Humans
Insulin - metabolism
Molecular and cellular biology
Mutation
Peptide Mapping
Phosphorylation
protein-tyrosine kinase
Protein-Tyrosine Kinases - metabolism
Receptor, Insulin - genetics
tyrosine
Tyrosine - metabolism
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Summary:Autophosphorylation of the insulin receptor has been previously documented to activate the phosphotransferase activity of the receptor from 20- to 200-fold. Biochemical studies have correlated activation of the receptor kinase with the autophosphorylation of tyrosines residues 1158, 1162, and 1163. To further assess the role of these 3 tyrosines in the activation process, we have studied the effect of their substitution with either the neutral amino acids phenylalanine or alanine or with the negatively charged amino acids aspartate and glutamate. In several other proteins, it has been shown that substitution of phosphorylated residues with negatively charged amino acids can mimic the phosphorylation state of the protein. In agreement with previous studies, tyrosines at positions 1162 and 1163 were found to be crucial in the kinase activation process. In contrast, mutant receptors with tyrosine 1158 changed to either phenylalanine or aspartate were still activated to the same extent as the wild-type receptor. An increased basal exogenous kinase activity was observed upon replacement of tyrosines 1162 and 1163 with, in increasing order of potency, aspartate = glutamate less than alanine = phenylalanine. These results indicate that phosphorylation of tyrosines 1162/1163 but not 1158 play a critical role in the activation of the receptor kinase and that the mechanism of activation of the receptor kinase by autophosphorylation is more complex than just an introduction of a cluster of negative charges in this region of the receptor. In addition, the finding of an increased basal kinase activity in receptors lacking tyrosines 1162 and 1163 could explain the reported ability of this receptor to mediate certain biological responses.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(17)35272-9