Atomic distance estimates from disulfides and high-affinity metal-binding sites in a K+ channel pore.
The pore of potassium channels is lined by four identical, highly conserved hairpin loops, symmetrically arranged around a central permeation pathway. Introduction of cysteines into the external mouth of the drk1 K channel pore resulted in the formation of disulfide bonds that were incompatible with channel function. Breaking these bonds restored function and resulted in a high-affinity Cd(2+)-binding site, indicating coordinated ligation by multiple sulfhydryls. Dimeric constructs showed that these disulfide bonds formed between subunits. These results impose narrow constraints on intersubunit atomic distances in the pore that strongly support a radial pore model. The data also suggest an important functional role for the outer mouth of the pore in gating or permeation.
Krovetz
H S
HS
Department of Pharmacology, Duke University Medical Center, Durham, North Carolina 27710, USA.
VanDongen
H M
HM
VanDongen
A M
AM
D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology; D003545:Cysteine; D051668:Delayed Rectifier Potassium Channels; D019281:Dimerization; D004220:Disulfides; D005260:Female; D008564:Membrane Potentials / Q000187:drug effects; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D015221:Potassium Channels / Q000737:chemistry* / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology
D051668:Delayed Rectifier Potassium Channels; D004220:Disulfides; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011994:Recombinant Proteins; D002104:Cadmium; D015032:Zinc; D003545:Cysteine