title: Na,K-ATPase: radiation inactivation studies.
abstract: Na,K-ATPase from duck salt gland and ox brain in the membrane-bound or solubilized form was studied by the radiation inactivation technique using ATP, CTP, GTP or p-NPP as substrates. The values of radiation inactivation size (RIS) were compared with the target size (TS) for the alpha-subunit of the enzyme obtained by an independent method as well as with analytical centrifugation data obtained for C12E8-solubilized enzyme. It was concluded that during ATP (CTP) hydrolysis the enzyme operates as an oligomeric structure; the complex formation requires the presence of K+ and adenosine triphosphate binding to the sites with a low affinity for the nucleotide. Specially designed experiments revealed that the degree of enzyme oligomerization increases with an increase in the microviscosity of the membrane lipid environment.
authors.affiliation: Department of Biochemistry, Moscow State University, U.S.S.R.
authors.forename: A A
authors.initials: AA
authors.lastname: Boldyrev
authors.forename: O D
authors.initials: OD
authors.lastname: Lopina
authors.forename: N U
authors.initials: NU
authors.lastname: Fedosova
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D003080:Cold Temperature; D003570:Cytidine Triphosphate / Q000378:metabolism; D004372:Ducks; D004789:Enzyme Activation / Q000528:radiation effects; D006160:Guanosine Triphosphate / Q000378:metabolism; D008051:Lipid Bilayers / Q000378:metabolism; D046911:Macromolecular Substances; D009596:Nitrophenols / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism / Q000528:radiation effects*; D014783:Viscosity
chemical_list: D008051:Lipid Bilayers; D046911:Macromolecular Substances; D009596:Nitrophenols; D009943:Organophosphorus Compounds; C008644:nitrophenylphosphate; D003570:Cytidine Triphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium