Cloning and expression of a human large-conductance calcium-activated potassium channel.
A putative BK channel gene was cloned from a human brain (substantia nigra) cDNA library by hybridization screening. The sequence of the full length clone shows high homology with the mSlo gene, suggesting that this cDNA is the human homologue (hSlo). The hSlo clone does not contain either alternative exon A or B at its splice sites; and similar to mSlo, it has a long string of serines at its 5' end. Reverse transcription coupled with the PCR technique demonstrated the differences in expression of the isoforms among the CNS and the periphery. Expression of hSlo in Xenopus oocytes showed a family of outward currents, induced by step depolarizations, that were blocked by iberiotoxin and activated by the compound NS004, a known opener of native and cloned maxi-K channels. Single channel recordings of hSlo channels showed a high degree of voltage- and Ca(2+)-dependence, and an average single channel conductance of 285.9 pS.
Dworetzky
S I
SI
Central Nervous System Drug Discovery, Dept., Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, CT 06492.
Trojnacki
J T
JT
Gribkoff
V K
VK
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001923:Brain Chemistry; D002118:Calcium / Q000502:physiology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons; D005260:Female; D005796:Genes; D006801:Humans; D015640:Ion Channel Gating; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008565:Membrane Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D009865:Oocytes; D010455:Peptides / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D024681:Potassium Channels, Calcium-Activated; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013378:Substantia Nigra / Q000737:chemistry*; D014982:Xenopus laevis
D018076:DNA, Complementary; C494841:KCNMA1 protein, human; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010455:Peptides; D024681:Potassium Channels, Calcium-Activated; D011993:Recombinant Fusion Proteins; C064719:iberiotoxin; D002118:Calcium