Analysis of glucagon-receptor interactions on isolated canine hepatocytes. Formation of reversibly and irreversibly cell-associated hormone.

摘要: We have investigated the interactions of ligand with canine hepatic glucagon receptor. Whereas time courses for radiolabeled binding to receptor and dissociation from revealed fast slow components at both 30 4 degrees C, a third component irreversibly cell-associated (nondissociable) only higher temperature. Related experiments identified that (a) initial rate formation nondissociable was slower than dissociably bound hormone; (b) fraction sites achieved plateau during extended incubations, whereas dissociable seen rise then slowly fall; (c) kinetics consistent linked, sequential reactions; (d) ligand-receptor complexes formed C were converted subsequent incubation (e) filled by prior cells unlabeled ligand. Analysis receptor-bound hormone resulting 125I-labeled selected concentrations either or [[127I]iodo-Tyr10]glucagon steady state in each case four ligand: those corresponding high low affinity nondissociably Implications these findings are considered terms mechanisms distribution among various glucagon-binding sites.