title: Endogenous protease mediated manifestations of a Ca2+-stimulated ATPase in purified dog gastric microsomes.
abstract: An endogenous soluble protease has been demonstrated to unmask a Ca2+-stimulated ATPase activity in purified dog gastric microsomes. The presence of ATP during protease treatment appears essential for the manifestation of the gastric Ca2+-stimulated ATPase activity. The endogenous protease appears to have trypsin-like activity, since soybean trypsin inhibitor completely blocks the protease effect. Manifestation of the Ca2+-stimulated ATPase occurs without affecting the microsomal (H+ + K+)-ATPase activity and associated H+ uptake ability. The unmasked Ca2+-stimulated ATPase appears insensitive to calmodulin. Possible roles of the enzyme in the regulation of gastric H+ transport have been discussed.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004285:Dogs; D004789:Enzyme Activation; D005750:Gastric Juice / Q000378:metabolism; D008861:Microsomes / Q000201:enzymology*; D013270:Stomach / Q000201:enzymology*; D013696:Temperature; D014357:Trypsin / Q000378:metabolism
chemical_list: D000255:Adenosine Triphosphate; D014357:Trypsin; D000252:Calcium-Transporting ATPases