title: Study of permeation and blocker binding in TMEM16A calcium-activated chloride channels.
abstract: We studied the effects of mutations of positively charged amino acid residues in the pore of X. tropicalis TMEM16A calcium-activated chloride channels: K613E, K628E, K630E; R646E and R761E. The activation and deactivation kinetics were not affected, and only K613E showed a lower current density. K628E and R761E affect anion selectivity without affecting Na(+) permeation, whereas K613E, R646E and the double mutant K613E + R646E affect anion selectivity and permeability to Na(+). Furthermore, altered blockade by the chloride channel blockers anthracene-9-carboxylic acid (A-9-C), 4, 4'-Diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) and T16inh-A01 was observed. These results suggest the existence of 2 binding sites for anions within the pore at electrical distances of 0.3 and 0.5. These sites are also relevant for anion permeation and blockade.
authors: a Departamento de Neurobiología Celular y Molecular ; Laboratorio de Neurobiología Molecular y Celular ; Instituto de Neurobiología . Campus UNAM Juriquilla; Querétaro, Qro . México.
authors: J P
authors: JP
authors: Reyes
authors: A
authors: A
authors: Huanosta-Gutiérrez
authors: A
authors: A
authors: López-Rodríguez
authors: A
authors: A
authors: Martínez-Torres
mesh_terms: D001665:Binding Sites / Q000187:drug effects; D065101:Chloride Channel Agonists / Q000737:chemistry / Q000494:pharmacology*; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010539:Permeability / Q000187:drug effects; D029867:Xenopus Proteins / Q000819:agonists* / Q000235:genetics / Q000378:metabolism*
chemical_list: D065101:Chloride Channel Agonists; D018118:Chloride Channels; D029867:Xenopus Proteins; C559904:xANO2 protein, Xenopus
keywords: 4,4'-Diisothiocyano-2,2'-stilbenedisulfonic acid; DIDS; TMEM16A; Xenopus tropicalis A-9-C; anthracene-9-carboxylic acid; calcium-activated chloride channels; ion permeation; pore; pore blockers