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Functional properties of a heterozygous mutation (Arg 1174 → Gln) in the tyrosine kinase domain of the insulin receptor from a Type A insulin resistant patient
Author(s) -
Moritz W.,
Froesch E.R.,
Böni-Schnetzler M.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00876-0
Subject(s) - autophosphorylation , insulin receptor , insulin receptor substrate , insulin , irs2 , medicine , endocrinology , tyrosine kinase , biology , receptor , phosphorylation , biochemistry , protein kinase a , insulin resistance
We analysed the biochemical properties of insulin receptors of a Type A insulin resistant patient with a single heterozygous point mutation substituting Gln for Arg 1174 . Insulin binding capacity and affinty to Epstein‐Barr virus transformed lymphocytes was normal. Quantitative analysis of autophosphorylation and substrate phosphorylation of soluble insulin receptors isolated from patient cells revealed no differences in the basal state whereas in the presence of insulin autophosphorylation activity was only 30% of control receptors. The stimulation of substrate phosphorylation and down‐regulation of receptors on patient cells after chronic exposure to insulin was diminished when compared to controls. We conclude that the heterozygous Arg 1174 mutation does not perturb basal kinase activity but specifically interferes with the kinase activation by insulin and that the mutation has a dominant negative effect on the wild type kinase.