Studies of biosynthesis of insulin by isolated perfused rat pancreas.

Incorporation studies with 3H-leucine have demonstrated that proinsulin is formed as a precursor of insulin in the perfused pancreas. A dependency of the insulin synthesis on the glucose concentration was revealed, based on a direct stimulation of the proinsulin synthesis. The conversion of proinsulin into insulin was not accelerated by glucose stimulation. The conversion also occurred in the absence of glucose.