TASK-5, a new member of the tandem-pore K(+) channel family.
TASKs are members of the recently identified K(+) channel family (KCNKx). Four TASKs (TASK1-4) identified so far form functional K(+) channels and encode background K(+) channels in various cell types. Recently, another member (TASK-5) was identified in the human genome. We cloned it and studied its tissue expression and functional properties. TASK-5 shares 51% amino acid identity with TASK-1 and TASK-3. Northern blot analysis showed that TASK-4 mRNA was expressed primarily in the adrenal gland and pancreas. Single nucleotide polymorphism (SNP) was found at amino acid position 95 that normally forms part of the K(+) channel selectivity filter. Neither form of TASK-5 showed channel activity when transfected in COS-7 cells. Exchange of C-termini of TASK-3 and TASK-5 failed to generate whole-cell currents. Thus, TASK-5 is a new member of the tandem-pore K(+) channel family but does not produce a functional plasma membrane K(+) current by itself.
Kim
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Department of Physiology and Biophysics, Finch University of Health Sciences/Chicago Medical School, 3333 Green Bay Road, North Chicago, Illinois 60064, USA. donghee.kim@finchcms.edu
Gnatenco
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D002874:Chromosome Mapping; D002890:Chromosomes, Human, Pair 20; D015894:Genome, Human; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D009419:Nerve Tissue Proteins; D018408:Patch-Clamp Techniques; D020641:Polymorphism, Single Nucleotide; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D024683:Potassium Channels, Tandem Pore Domain; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
C431132:KCNK15 protein, human; C423407:KCNK17 protein, human; C498655:KCNK9 protein, human; C486605:Kcnk15 protein, rat; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C420132:potassium channel subfamily K member 3