A pore segment in DEG/ENaC Na(+) channels.
DEG/ENaC Na(+) channels have diverse functions, including Na(+) absorption, neurotransmission, and sensory transduction. The ability of these channels to discriminate between different ions is critical for their normal function. Several findings suggest that DEG/ENaC channels have a pore structure similar to K(+) channels. To test this hypothesis, we examined the accessibility of native and introduced cysteines in the putative P loop of ENaC. We identified residues that span a barrier that excludes amiloride as well as anionic and large methanethiosulfonate reagents from the pore. This segment contains a structural element ((S/G)CS) involved in selectivity of ENaC. The results are not consistent with predictions from the K(+) channel pore, suggesting that DEG/ENaC Na(+) channels have a novel pore structure.
Snyder
P M
PM
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA. psnyder@blue.weeg.uiowa.edu
Olson
D R
DR
Bucher
D B
DB
D000595:Amino Acid Sequence; D003545:Cysteine / Q000235:genetics; D053503:Epithelial Sodium Channels; D005020:Ethyl Methanesulfonate / Q000737:chemistry; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D017386:Sequence Homology, Amino Acid; D015222:Sodium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D053503:Epithelial Sodium Channels; D015222:Sodium Channels; D005020:Ethyl Methanesulfonate; D003545:Cysteine