Abstract
We have cloned and expressed a Ca(2+)-activated K+ channel beta-subunit from human brain. The open reading frame encodes a 191-amino acid protein possessing significant homology to a previously described subunit cloned from bovine muscle. The gene for this subunit is located on chromosome 5 at band q34 (hslo-beta). There is no evidence for alternative RNA splicing of this gene product. hslo-beta mRNA is abundantly expressed in smooth muscle, but expression levels are low in most other tissues, including brain. Brain subregions in which beta-subunit mRNA expression is relatively high are the hippocampus and corpus callosum. The coexpression of hslo-beta mRNA together with hslo-alpha subunits in either Xenopus oocytes or stably transfected HEK 293 cells give rise to Ca(2+)-activated potassium currents with a much increased calcium and/or voltage sensitivity. These data indicate that the beta-subunit shows a tissue distribution different to that of the alpha-subunit, and in many tissues there may be no association of alpha-subunits with beta-subunits. These beta-subunits can play a functional role in the regulation of neuronal excitability by tuning the Ca2+ and/or the voltage dependence of alpha-subunits.
Publication types
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Comparative Study
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Brain Chemistry / genetics*
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Calcium / pharmacology*
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Cattle
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Chromosome Mapping
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Chromosomes, Human, Pair 5 / genetics
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Cloning, Molecular
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Corpus Callosum / chemistry
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Hippocampus / chemistry
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Humans
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In Situ Hybridization, Fluorescence
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Ion Channel Gating*
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Large-Conductance Calcium-Activated Potassium Channel alpha Subunits
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Large-Conductance Calcium-Activated Potassium Channel beta Subunits
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Large-Conductance Calcium-Activated Potassium Channels
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Molecular Sequence Data
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Patch-Clamp Techniques
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Potassium Channels / biosynthesis
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Potassium Channels / drug effects
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Potassium Channels / genetics*
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Potassium Channels, Calcium-Activated*
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RNA, Messenger / isolation & purification
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Recombinant Proteins / biosynthesis
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Sequence Homology, Amino Acid
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Species Specificity
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Tissue Distribution
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Xenopus
Substances
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Large-Conductance Calcium-Activated Potassium Channel alpha Subunits
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Large-Conductance Calcium-Activated Potassium Channel beta Subunits
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Large-Conductance Calcium-Activated Potassium Channels
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Potassium Channels
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Potassium Channels, Calcium-Activated
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RNA, Messenger
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Recombinant Proteins
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Calcium
Associated data
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GENBANK/U42600
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GENBANK/U42601
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GENBANK/U42602
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GENBANK/U42603