Characterization of TASK-4, a novel member of the pH-sensitive, two-pore domain potassium channel family.
We report the primary sequence of TASK-4, a novel member of the acid-sensitive subfamily of tandem pore K(+) channels. TASK-4 transcripts are widely expressed in humans, with highest levels in liver, lung, pancreas, placenta, aorta and heart. In Xenopus oocytes TASK-4 generated K(+) currents displaying a marked outward rectification which was lost by elevation of extracellular K(+). TASK-4 currents were efficiently blocked by barium (83% inhibition at 2 mM), only weakly inhibited by 1 mM concentrations of quinine, bupivacaine and lidocaine, but not blocked by tetraethylammonium, 4-aminopyridine and Cs(+). TASK-4 was sensitive to extracellular pH, but in contrast to other TASK channels, pH sensitivity was shifted to more alkaline pH. Thus, TASK-4 in concert with other TASK channels might regulate cellular membrane potential over a wide range of extracellular pH.
Aventis Pharma Deutschland GmbH, DG Cardiovascular Diseases, D-65926 Frankfurt am Main, Germany.
N
N
Decher
M
M
Maier
W
W
Dittrich
J
J
Gassenhuber
A
A
Brüggemann
A E
AE
Busch
K
K
Steinmeyer
D000595:Amino Acid Sequence; D000818:Animals; D001283:Atrioventricular Node / Q000378:metabolism; D001464:Barium / Q000494:pharmacology; D003001:Cloning, Molecular; D004594:Electrophysiology; D006325:Heart Atria / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009865:Oocytes; D010802:Phylogeny; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism; D024683:Potassium Channels, Tandem Pore Domain; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D014982:Xenopus laevis
C423407:KCNK17 protein, human; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D001464:Barium