title: Occlusion of Na+ by the Na,K-ATPase in the presence of oligomycin.
abstract: Oligomycin occludes Na+ in an E1-form of the Na,K-ATPase. The rate constants for the release of Na+ from the E1-form and for the transition to the E2-form are about 0.5 s-1. The effect of oligomycin is not seen using other cations which also have a Na+-like effect on the enzyme conformation. The inhibitory effect of oligomycin on the ADP-ATP dependent Na:Na exchange but not on the accompanying ADP-ATP exchange can be explained from a decrease in the rate of release of Na+ from an E1 approximately phosphoform with Na+ occluded, E'1 approximately P (Na3), i.e. with Na+ in the membrane phase, to an E"1 approximately PNa3 form with Na+ not occluded. E"1 approximately PNa3 is at a step before formation of E2-P, and disappears at a high rate when ADP reacts with E"1 approximately P (Na3).
authors.forename: M
authors.initials: M
authors.lastname: Esmann
authors.forename: J C
authors.initials: JC
authors.lastname: Skou
mesh_terms: D000818:Animals; D004284:Dogfish; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009840:Oligomycins / Q000378:metabolism / Q000494:pharmacology*; D010766:Phosphorylation; D011487:Protein Conformation / Q000187:drug effects; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
chemical_list: D009840:Oligomycins; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium