Binding and internalization of 125I-glucagon in hepatocytes of intact mouse liver. An autoradiographic study

Localization of labeled material in hepatocytes of intact mouse liver injected via the portal vein with 125I-glucagon was studied. At 3 minutes after pulse injection of the labeled glucagon, most grains were localized associated with the plasma membrane. At 10 min after the injection, the grains were distributed throughout the cytoplasm and did not appear localized exclusively in any specific cell organelles. At 20 min after the injection, the labeled material appeared decreased, and was not yet localized exclusively in any specific cell organelles. Thus, in hepatocytes of intact liver, labeled glucagon is internalized more rapidly than in freshly isolated hepatocytes (Barazzone et al. 1980), and there appear to be no cell organelles in which internalized glucagon is preferentially localized.