Metabolism of Asialotranscortin by Hepatocytes and Cortisol Binding to Hepatocytes

Abstract

Binding and catabolism of iodinated human transcortin and asialotranscortin were studied in isolated rat hepatocytes. Human transcortin binding to hepatocytes was very low (< 3%) while 40–60% of the asialotranscortin bound to the hepatocytes, Asialofetuin inhibited asialotranscortin binding to hepatocytes, producing 50% inhibition of binding at 5 × 10⁻⁹M, but had no effect on transcortin binding. The lysosomal inhibitors leupeptin (0.05 mM) and ammonium chloride (10 mM) had no effect on asialotranscortin binding but prevented the latter's catabolism, suggesting lysosomal involvement in asialotranscortin degradation. Both transcortin and asialotranscortin inhibited the binding of [³H]Cortisol to the hepatocytes in a dose-dependent manner.