THE SIGNIFICANCE OF THE BINDING OF INSULIN-TO CYTOSTRUCTURAL ELEMENTS OF RAT LIVER131

Abstract
Insulin-I131 has been intravenously administered in tracer doses to rats and its intracellular distribution determined. It was found that the major portion of the intracellular I131 was bound to mitochondria and microscomes. This bound insulin-I131 was completely precipitable with TCA and could not be removed by washing. Furthermore, in comparison to unbound insulin-I131, it was less susceptible to endogenous degradative processes as well as those accomplished with added "insulinase." The significance of these observations on the hepatic fate of insulin-I131 is discussed in reference to the insulin economy of the body, as a whole, and the liver, in particular.