An extracellular acidic cleft confers profound H⁺-sensitivity to epithelial sodium channels containing the δ-subunit in Xenopus laevis.

ABSTRACT: The limited sodium availability of freshwater and terrestrial environments was a major physiological challenge during vertebrate evolution. The epithelial sodium channel (ENaC) is present in the apical membrane of sodium-absorbing vertebrate epithelia and evolved as part of a machinery for efficient sodium conservation. ENaC belongs to the degenerin/ENaC protein family and is the only member that opens without an external stimulus. We hypothesized that ENaC evolved from a proton-activated sodium channel present in ionocytes of freshwater vertebrates and therefore investigated whether such ancestral traits are present in ENaC isoforms of the aquatic pipid frog Xenopus laevis Using whole-cell and single-channel electrophysiology of Xenopus oocytes expressing ENaC isoforms assem

SUBMITTER: Wichmann L 

PROVIDER: S-EPMC6699844 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature