Displacement of the Na⁺/K⁺ pump's transmembrane domains demonstrates conserved conformational changes in P-type 2 ATPases.

ABSTRACT: Cellular survival requires the ion gradients built by the Na⁺/K⁺ pump, an ATPase that alternates between two major conformations (E1 and E2). Here we use state-specific engineered-disulfide cross-linking to demonstrate that transmembrane segment 2 (M2) of the pump's α-subunit moves in directions that are inconsistent with distances observed in existing crystal structures of the Na⁺/K⁺ pump in E1 and E2. We characterize this movement with voltage-clamp fluorometry in single-cysteine mutants. Most mutants in the M1-M2 loop produced state-dependent fluorescence changes upon labeling with tetramethylrhodamine-6-maleimide (TMRM), which were due to quenching by multiple endogenous tryptophans. To avoid complications arising from multiple potential quen

SUBMITTER: Young VC 

PROVIDER: S-EPMC7923365 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature