Control of insulin receptor affinity by a Ca2+-sensitive binding site.
Calcium (Ca2+) increased insulin-receptor binding in both membrane and solubilised receptor preparations. Ca2+ increased both receptor affinity and initial rate of association of [125I]insulin to the receptor preparations. Ca2+ had no effect on insulin receptor number in either receptor preparation. The effect of Ca2+ on affinity could be mimicked by ions with similar ionic radii and properties (e.g., Ba2+, Mg2+ and Sr2+). EDTA and oleic acid reduced insulin binding and receptor affinity and these effects were reversed by the addition of Ca2+. These studies suggest that Ca2+ and Ca2+-like ions may bind to a site on or near the receptor and may be responsible for a conformational change with a consequent increase in receptor affinity.
D002118:Calcium / Q000494:pharmacology*; D002413:Cations, Divalent; D002462:Cell Membrane / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007700:Kinetics; D019301:Oleic Acid; D009829:Oleic Acids / Q000494:pharmacology; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D011972:Receptor, Insulin / Q000187:drug effects / Q000378:metabolism*
D002413:Cations, Divalent; D007328:Insulin; D009829:Oleic Acids; D019301:Oleic Acid; D004492:Edetic Acid; D011972:Receptor, Insulin; D002118:Calcium