Mutagenesis of lysine 460 in the human insulin receptor. Effects upon receptor recycling and cooperative interactions among binding sites.

摘要: Mutations in the insulin receptor gene can cause resistance. Previously, we have identified a mutation substituting glutamic acid for lysine at position 460 alpha-subunit of patient with genetic form In present work, investigated effect upon function amino substitutions 460. Decreasing pH from 8.0 to 5.5 caused progressive acceleration dissociation 125I-insulin wild-type receptor. Substitution acidic acids (Glu or Asp) Lys460 decreased ability accelerate 125I-insulin. contrast, substitution Arg neutral (Val, Met, Thr, Gln) had no sensitivity pH. Correlated pH, Glu Asp retarded intracellular receptors subsequent receptor-mediated endocytosis. Furthermore, retardation internalized was associated half-life summary, Glu460 appears resistance by accelerating degradation and, thereby, decreasing number on cell surface. Additional studies suggested that may provide groups whereby disuccinimidyl suberate cross-links two alpha-subunits each other. Consistent hypothesis is located interface between adjacent alpha-subunits, impair cooperative interactions among binding sites. The decreases positively interactions; Arg460 impairs negative cooperativity. did not decrease stimulate tyrosine kinase.