title: Cryo-EM structure of the open high-conductance Ca2+-activated K+channel.
abstract: The Ca2+-activated K+channel, Slo1, has an unusually large conductance and contains a voltage sensor and multiple chemical sensors. Dual activation by membrane voltage and Ca2+renders Slo1 central to processes that couple electrical signalling to Ca2+-mediated events such as muscle contraction and neuronal excitability. Here we present the cryo-electron microscopy structure of a full-length Slo1 channel from Aplysia californica in the presence of Ca2+and Mg2+at a resolution of 3.5 Å. The channel adopts an open conformation. Its voltage-sensor domain adopts a non-domain-swapped attachment to the pore and contacts the cytoplasmic Ca2+-binding domain from a neighbouring subunit. Unique structural features of the Slo1 voltage sensor suggest that it undergoes different conformational changes than other known voltage sensors. The structure reveals the molecular details of three distinct divalent cation-binding sites identified through electrophysiological studies of mutant Slo1 channels.
authors.affiliation: Rockefeller University and Howard Hughes Medical Institute, 1230 York Avenue, New York, New York 10065, USA.
authors.forename: Xiao
authors.initials: X
authors.lastname: Tao
authors.affiliation: Rockefeller University and Howard Hughes Medical Institute, 1230 York Avenue, New York, New York 10065, USA.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Hite
authors.affiliation: Rockefeller University and Howard Hughes Medical Institute, 1230 York Avenue, New York, New York 10065, USA.
authors.forename: Roderick
authors.initials: R
authors.lastname: MacKinnon
mesh_terms: D000494:Allosteric Regulation / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D001048:Aplysia / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure*; D001665:Binding Sites / Q000187:drug effects; D002118:Calcium / Q000737:chemistry / Q000494:pharmacology; D002413:Cations, Divalent / Q000378:metabolism; D020285:Cryoelectron Microscopy; D003593:Cytoplasm / Q000378:metabolism; D055724:Electrophysiological Phenomena; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure*; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008274:Magnesium / Q000737:chemistry / Q000494:pharmacology; D008958:Models, Molecular; D000072417:Protein Domains / Q000187:drug effects; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008051:Lipid Bilayers; D021122:Protein Subunits; D008274:Magnesium; D002118:Calcium