[ADH and cAMP receptor binding in the kidney medulla of mice insensitive to ADH]

Specific binding of ADH by the membrane fraction of the kidney medulla was lower in the normal CBA mice than in mutant mice with nephrogenic diabetes. Gel filtration of the solubilized ADH receptors of mutants revealed the presence of an unidentified factor which caused cooperative binding of ADH. DEAE-chromatography revealed no difference between cytosolic cAMP receptors in normal and mutant animals. Assay of GTP-ase activity of the membrane fraction revealed that ADH increased this parameter in CBA mice but not in mutant animals. Cholera toxin significantly diminished membrane ATP-ase activity whereas membrane preparations from mutant mice developed a reactivity to ADH. GTP binding ability in these preparations was higher than inn intact ones. In CBA mice this ability increased dramatically. HPLC profiles of G-protein complexes with GNP were very different in CBA and mutant mice. Mutation seems to cause changes both in binding and in "cross-talk" link op-complex membrane receptor of ADH.