Sulphydryl agents modulate insulin- and epidermal growth factor (EGF)-receptor kinase via reaction with intracellular receptor domains: differential effects on basal versus activated receptors

摘要: Sulphydryl reagents have been shown to produce a variety of effects on insulin-receptor structure and function. However, localization these specific receptor domains has not attempted. We investigated this question with insulin- epidermal growth factor (EGF)-receptors (both are tyrosine kinases but different sulphydryl/disulphide structures within the external domain), insulin kinase (IRK) protein consisting solely cytoplasmic domain exhibiting constitutive activity. Results showed differential response between basal activated receptors. The physiological reductant GSH stimulated autophosphorylation, was either without effect (EGF) or inhibited (insulin) receptors, occurred visible reduction structure. These results contrast those obtained dithiothreitol which appears activate phosphorylation in association extracellular disulphides, is EGF IRK protein. Alkylating agents N-ethylmaleimide (NEM) iodoacetamide (IAM) had opposing autophosphorylation. only state IAM able protect receptors from inhibitory NEM. Our suggest that complex sulphydryl interactions can occur EGF-receptors alter same respect reagent action, possibly due conformational change induced by ligand (insulin, EGF) activation.