Rings of charge within the extracellular vestibule influence ion permeation of the 5-HT3A receptor.

ABSTRACT: The determinants of single channel conductance (γ) and ion selectivity within eukaryotic pentameric ligand-gated ion channels have traditionally been ascribed to amino acid residues within the second transmembrane domain and flanking sequences of their component subunits. However, recent evidence suggests that γ is additionally controlled by residues within the intracellular and extracellular domains. We examined the influence of two anionic residues (Asp(113) and Asp(127)) within the extracellular vestibule of a high conductance human mutant 5-hydroxytryptamine type-3A (5-HT(3)A) receptor (5-HT(3)A(QDA)) upon γ, modulation of the latter by extracellular Ca(2+), and the permeability of Ca(2+) with respect to Cs(+) (P(Ca)/P(Cs)). Mutations neutralizing (Asp → Asn), or reversing (Asp → Lys),

SUBMITTER: Livesey MR 

PROVIDER: S-EPMC3091210 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature