title: The interaction of caerulein with the rat pancreas. 1. Specific binding of [3H]caerulein on plasma membranes and evidence for negative cooperativity.
abstract: 1. The binding of [3H]caerulein (a stable, biologically active labeled analog of cholecystokinin-pancreozymin) to semi-purified rat pancreatic plasma membranes was investigated. The binding was dependent on time and temperature, as well as saturable, specific and reversible. This process was pH-dependent and optimal at pH 7.0. Cysteine and serine residues in plasma membranes were of importance for binding. Mg2+ favored the binding. 2. The acceleration of the dissociation of [3H]caerulein in the presence of an excess of native caerulein suggests that binding was characterized by a negative cooperativity. The fast dissociation state evoked by a high degree of occupancy by caerulein was inhibited by lowering the temperature, by decreasing the pH, or by the presence of wheat germ agglutinin.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002108:Ceruletide / Q000378:metabolism*; D007700:Kinetics; D010179:Pancreas / Q000378:metabolism*; D051381:Rats; D011955:Receptors, Drug / Q000378:metabolism*; D013696:Temperature
chemical_list: D011955:Receptors, Drug; D002108:Ceruletide