title: K+ pore structure revealed by reporter cysteines at inner and outer surfaces.
abstract: The structure of the carboxyl half of the pore-forming region of Kv2.1 was studied by replacing each of 15 consecutive residues between positions 383 and 369 with a reporter cysteine residue. Extracellular application of charged, membrane-impermeant methanethiosulfonates irreversibly modified currents at four cysteine-substituted positions, K382, Y380, I379, and D378. Intracellular exposure to methanethiosulfonate ethyltrimethylammonium revealed another set of reactive mutants (V374, T373, T372, and T370). Our results indicate that positions 378 and 374 are exposed at outer and inner mouths of the channel, respectively, and immersed in the aqueous phase. In contrast to present topological models, the 383-369 region appears to span the pore mainly as a nonperiodic structure.
authors.affiliation: Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Pascual
authors.forename: C C
authors.initials: CC
authors.lastname: Shieh
authors.forename: G E
authors.initials: GE
authors.lastname: Kirsch
authors.forename: A M
authors.initials: AM
authors.lastname: Brown
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003545:Cysteine / Q000737:chemistry*; D004553:Electric Conductivity; D005260:Female; D015870:Gene Expression; D046911:Macromolecular Substances; D008698:Mesylates / Q000494:pharmacology; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009865:Oocytes / Q000378:metabolism; D016133:Polymerase Chain Reaction; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D018075:RNA, Complementary / Q000235:genetics; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014981:Xenopus
chemical_list: D046911:Macromolecular Substances; D008698:Mesylates; D015221:Potassium Channels; D018075:RNA, Complementary; D011994:Recombinant Proteins; D013757:Tetraethylammonium Compounds; C074502:methanethiosulfonate; D019789:Tetraethylammonium; D003545:Cysteine