Anti-insulin receptor antibodies mimic the effects of insulin on the activities of pyruvate-dehydrogenase and acetylCoA carboxylase and on specific protein-phosphorylation in rat epididymal fat-cells

Autoantibodies against insulin [I] receptors found in certain patients with severe I resistance stimulate glucose transport and metabolism in fat cell and muscle preparations. Preincubation of rat epididymal adipose tissue with 1:1000 dilution of one such serum apparently results in a 2-fold increase in the initial activities of pyruvate dehydrogenase and acetylCoA carboxylase. These increases are similar to the maximum effects of I. Incubation of isolated fat cells with the serum at the same concentration also resulted in the increased phosphorylation of 3 intracellular proteins with subunit MW of 130,000, 35,000 and 22,000 to the same extent as observed with I. The short term effects of I apparently do not involve the entry of the I molecule (or part thereof) into cells of target tissues.