[Molecular biology of regulation of renal function--structure, function and distribution of the receptor--insulin, glucagon]

Abstract

Insulin and glucagon are known to regulate both metabolic and transport functions in the nephron, directly. Insulin receptor is a heterotetrameric glycoprotein, consisting of two alpha-subunits and two beta-subunits linked by disulfide bonds. Binding of insulin to its receptor in the proximal basolateral membranes results in phosphorylation of beta-subunit which is considered to be necessary to subsequent activation of receptor tyrosine kinase. Insulin receptors are also present in the luminal membranes of the proximal tubules. Proximal tubules are major sites of insulin and glucagon degradation. Insulin and glucagon regulate mineral transport mainly at the thick ascending limb. Insulin and glucagon regulate gluconeogenesis in the kidney.