Institut for Biomedicin

Mikael Esmann

Occlusion of Na+ by the Na,K-ATPase in the presence of oligomycin

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  • Institut for Fysiologi og Biofysik
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).
OriginalsprogEngelsk
TidsskriftBiochemical and Biophysical Research Communications
Vol/bind127
Nummer3
Sider (fra-til)857-863
Antal sider7
ISSN0006-291X
StatusUdgivet - 29 mar. 1985

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