Distinct effects of Q925 mutation on intracellular and extracellular Na⁺ and K⁺ binding to the Na⁺, K⁺-ATPase.

ABSTRACT: Three Na⁺ sites are defined in the Na⁺-bound crystal structure of Na⁺, K⁺-ATPase. Sites I and II overlap with two K⁺ sites in the K⁺-bound structure, whereas site III is unique and Na⁺ specific. A glutamine in transmembrane helix M8 (Q925) appears from the crystal structures to coordinate Na⁺ at site III, but does not contribute to K⁺ coordination at sites I and II. Here we address the functional role of Q925 in the various conformational states of Na⁺, K⁺-ATPase by examining the mutants Q925A/G/E/N/L/I/Y. We characterized these mutants both enzymatically and electrophysiologically, thereby revealing their Na⁺ and K⁺ binding properties. Remarkably,

SUBMITTER: Nielsen HN 

PROVIDER: S-EPMC6746705 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature