title: Target molecular weight of the gastric (H+ + K+)-ATPase functional and structural molecular size.
abstract: The state of assembly of the (H+ + K+)-ATPase in purified hog gastric mucosa membranes was studied by target size analysis applied to radiation-induced enzyme inactivation and polypeptide degradation data. Radiation inactivated the Mg2+-ATPase, K+-stimulated ATPase, and p-nitrophenyl phosphatase activities of the membrane preparation with a dose dependence characteristic of a target size of 270,000-daltons. Radiation also bleached the major 100,000-dalton sodium dodecyl sulfate-gel electrophoresis band of this preparation, indicating a radiation-induced degradation. This apparent polypeptide degradation exhibited a dose dependency corresponding to a target size of 250,000 daltons in situ. It is suggested that the gastric ATPase is a trimeric assembly of the 100,000-dalton polypeptides.
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000528:radiation effects; D000818:Animals; D005753:Gastric Mucosa / Q000201:enzymology*; D017506:H(+)-K(+)-Exchanging ATPase; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D013552:Swine
chemical_list: D046911:Macromolecular Substances; D000251:Adenosine Triphosphatases; D017506:H(+)-K(+)-Exchanging ATPase