Absence of covalent binding by insulin to erythrocyte and reticulocyte insulin receptors

Abstract

We investigated whether insulin forms covalent bonds with its receptors on erythrocytes and reticulocytes, as it does in adipocytes (1). Of the [125I]-insulin specifically bound at 37°C to human and rat erythrocytes and rat reticulocytes, only 1.5 - 2.3% was non-dissociable on extensive washing. When ghosts prepared from the washed cells were solubilized in Triton X-100, only 0.6 - 1.5% of the specifically bound radioactivity appeared in the void volume of a Sephadex G-50 column. Moreover in contrast to adipocytes, this high molecular weight radioactivity was not immunoprecipitable by antibodies to the insulin receptor and was dissociated during chromatography in sodium dodecyl sulphate. Thu..