ATP-dependent calcium transport in rat parotid microsomes. I. Localization, properties, Ca2+-ATPase activity and phosphoenzyme formation.
ATP-dependent Ca2+ transport was studied in rat parotid microsomes; the activity appears to be associated with rough endoplasmic reticulum vesicles, as indicated by marker distribution in subcellular fractions and by electron microscopic observations. Purified rough microsomes exhibit an ATP-dependent Ca2+ accumulation and a Ca2+-dependent ATPase activity; these activities are similarly stimulated by K+ and display an apparent Km for free calcium of 0.6-0.7 microM. A phosphoprotein, with a molecular weight of about 110,000, was detected after short incubation with [gamma 32P] ATP and CaCl2; it is suggested that this compound represents a phosphorylated intermediate form of the Ca2+-ATPase.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002132:Calcium Radioisotopes; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002458:Cell Fractionation; D004533:Egtazic Acid / Q000494:pharmacology; D007700:Kinetics; D008854:Microscopy, Electron; D008861:Microsomes / Q000201:enzymology* / Q000648:ultrastructure; D010306:Parotid Gland / Q000201:enzymology* / Q000648:ultrastructure; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats
D002132:Calcium Radioisotopes; D010750:Phosphoproteins; D000001:Calcimycin; D004533:Egtazic Acid; D000252:Calcium-Transporting ATPases; D002118:Calcium