An ion selectivity filter in the extracellular domain of Cys-loop receptors reveals determinants for ion conductance.

ABSTRACT: Neurotransmitter binding to Cys-loop receptors promotes a prodigious transmembrane flux of several million ions/s, but to date, structural determinants of ion flux have been identified flanking the membrane-spanning region. Using x-ray crystallography, sequence analysis, and single-channel recording, we identified a novel determinant of ion conductance near the point of entry of permeant ions. Co-crystallization of acetylcholine-binding protein with sulfate anions revealed coordination of SO4(2-) with a ring of lysines at a position equivalent to 24 A above the lipid membrane in homologous Cys-loop receptors. Analysis of multiple sequence alignments revealed that residues equivalent to the ring of lysines are negatively charged in cation-selective receptors but are positively charged in an

SUBMITTER: Hansen SB 

PROVIDER: S-EPMC2662287 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature