title: [Assessment of the role of endogenous regulators in the activation of Ca-ATPase in erythrocyte membranes].
abstract: The contribution of calmodulin and protein kinases A or C to the activation of membrane Ca-ATPase was studied on saponin-permeabilized rat erythrocytes. In the presence of all endogenous regulators, the dependence of the Ca-ATPase activity of Ca2+ concentration was described by a bell-shaped curve with a maximum at 2-5 microM Ca2+; K0.5 = 0.43 microM Ca2+. Washing of erythrocyte membranes with 5-10 microM Ca2+ maintained up to 75% of the ATPase activity, while washing with EGTA (2 mM) decreased the activity, on the average, 5-fold, and increased K0.5 up to 0.54-0.6 microM Ca2+. An addition of an EGTA extract to washed membranes restored up to 75% of the original ATPase activity, while calmodulin restored about 40% of the original Ca-ATPase activity and decreased K0.5 to 0.23-0.3 microM Ca2+. The calmodulin inhibitor R24571 failed to alter the Ca-ATPase activity in permeabilized erythrocytes but slightly diminished it in reconstituted membranes. The protein kinase C inhibitors H7 and polymyxin increased the Ca-ATPase activity in permeabilized red cells and suppressed it in reconstituted membranes. The data obtained suggest that in native red cell membranes Ca-ATPase is activated by regulator(s) dependent on Ca2+ and protein kinase which are other than calmodulin.
authors.forename: V V
authors.initials: VV
authors.lastname: Petruniaka
authors.forename: E P
authors.initials: EP
authors.lastname: Severina
authors.forename: S N
authors.initials: SN
authors.lastname: Orlov
authors.forename: T A
authors.initials: TA
authors.lastname: Bezlepkina
authors.forename: E A
authors.initials: EA
authors.lastname: Paniushkina
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism; D004789:Enzyme Activation; D004910:Erythrocyte Membrane / Q000201:enzymology*; D007093:Imidazoles / Q000494:pharmacology; D008274:Magnesium / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002147:Calmodulin; D007093:Imidazoles; C031938:calmidazolium; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D000252:Calcium-Transporting ATPases; D008274:Magnesium; D002118:Calcium
vernacular_title: Otsenka roli éndogennykh reguliatorov v aktivatsii Ca-ATPazy membran éritrotsitov.