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Transporter Information:
Name: potassium channel, subfamily K, member 15
Symbol: KCNK15
TC: 1.A.1.9.1
Locations: 20q12-20q13
Aliases: LOC64181, dJ781B1.1, KT3.3, KIAA0237, TASK5, TASK-5, HGNC:13640, HGNC:6276
GenBank: AF257081
Swiss-Prot: Q9H427
Accession Number: NM_022358
PubMed (11409881): Kim D, Gnatenco C. TASK-5, a new member of the tandem-pore K(+) channel family.Biochem Biophys Res Commun. 2001 Jun 22;284(4):923-30. PMID: 11409881 [PubMed - indexed for MEDLINE]

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.

PubMed (11431495): Vega-Saenz de Miera E, Lau DH, Zhadina M, Pountney D, Coetzee WA, Rudy B. KT3.2 and KT3.3, two novel human two-pore K(+) channels closely related toTASK-1.J Neurophysiol. 2001 Jul;86(1):130-42. PMID: 11431495 [PubMed - indexed for MEDLINE]

We report the cloning of human KT3.2 and KT3.3 new members of the two-pore K(+) channel (KT) family. Based on amino acid sequence and phylogenetic analysis, KT3.2, KT3.3, and TASK-1 constitute a subfamily within the KT channel mammalian family. When Xenopus oocytes were injected with KT3.2 cRNA, the resting membrane potential was brought close to the potassium equilibrium potential. At low extracellular K(+) concentrations, two-electrode voltage-clamp recordings revealed the expression of predominantly outward currents. With high extracellular K(+) (98 mM), the current-voltage relationship exhibited weak outward rectification. Measurement of reversal potentials at different [K(+)](o) revealed a slope of 48 mV per 10-fold change in K(+) concentration as expected for a K(+)-selective channel. Unlike TASK-1, which is highly sensitive to changes of pH in the physiological range, KT3.2 currents were relatively insensitive to changes in intracellular or extracellular pH within this range due to a shift in the pH dependency of KT3.2 of 1 pH unit in the acidic direction. On the other hand, the phorbol ester phorbol 12-myristate 13-acetate (PMA), which does not affect TASK-1, produces strong inhibition of KT3.2 currents. Human KT3.2 mRNA expression was most prevalent in the cerebellum. In rat, KT3.2 is exclusively expressed in the brain, but it has a wide distribution within this organ. High levels of expression were found in the cerebellum, medulla, and thalamic nuclei. The hippocampus has a nonhomogeneous distribution, expressing at highest levels in the lateral posterior and inferior portions. Medium expression levels were found in neocortex. The KT3.2 gene is located at chromosome 8q24 1-3, and the KT3.3 gene maps to chromosome 20q13.1.

>sp|Q9H427|KCNKF_HUMAN Potassium channel subfamily K member 15 OS=Homo sapiens GN=KCNK15 PE=1 SV=2