External Ion Access in the Na/K Pump: Kinetics of Na⁺, K⁺, and Quaternary Amine Interaction.

ABSTRACT: Na/K pumps build essential ion gradients across the plasmalemma of animal cells by coupling the extrusion of three Na⁺, with the import of two K⁺ and the hydrolysis of one ATP molecule. The mechanisms of selectivity and competition between Na⁺, K⁺, and inhibitory amines remain unclear. We measured the effects of external tetrapropylammonium (TPA⁺) and ethylenediamine (EDA²⁺) on three different Na/K pump transport modes in voltage-clamped Xenopus oocytes: 1) outward pump current (I_P), 2) passive inward H⁺ current at negative voltages without Na⁺ or K⁺ (I_H), and 3) transient charge movement reporting the voltage-dependent extracellular binding/release of Na⁺ (Q<

SUBMITTER: Stanley KS 

PROVIDER: S-EPMC6051257 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature