TABLE 8

K2P9.1 channels

Channel name K2P9.1
Description Two-pore domain potassium channel subunit; open rectifier
Other names KCNK9, TASK-3
Molecular information Human: 374aa, NM_016601, chr0.8q24-3, KCNK9,1,2,3 GeneID: 51305, PMID:10734076
Rat: 395aa, NM_053405, kcnk9
Mouse: not cloned
Associated subunits 14-3-3 (see “Comments”)7,8
Functional assays Electrophysiological1,2,3,5,6,7,8,9,10,11
Current Not established (see “Comments”)
Conductance 27pS (see “Comments”)
Ion selectivity Not established
Activation See “Comments”
Inactivation See “Comments”
Activators None
Gating inhibitors None
Blockers External pH (6.5),3 ruthenium red (700 nM)8
Radioligands None
Channel distribution Brain (see “Comments”)1
Physiological functions See “Comments”4,5,6
Mutations and pathophysiology Not established
Pharmacological significance Not established
Comments Activation and deactivation with voltage steps seem to be instantaneous; the guinea pig variant is reported to have the same conductance and distribution as human and a conductance of 60pS; Northern blot analysis suggests that rat K2P9.1 expression outside the CNS is extremely low, as is noted for the human and guinea pig gene; K2P9 gene is amplified in several human carcinomas, and overexpression of K2P9 protein in cell lines promotes tumor formation4,5; like K2P3, surface expression of K2P9 depends on its association with 14-3-3 to release it from the endoplasmic reticulum7,8; potential heterodimerization of K2P9 is discussed under K2P39

  • aa, amino acids; chr., chromosome; CNS, central nervous system.

  • ↵1. Chapman CG, Meadows HJ, Godden RJ, Campbell DA, Duckworth M, Kelsell RE, Murdock PR, Randall AD, Rennie GI, and Gloger IS (2000) Cloning, localisation and functional expression of a novel human, cerebellum specific, two pore domain potassium channel. Mol Brain Res 82:74-83

  • ↵2. Kim Y, Bang H, and Kim D (2000) TASK-3, a new member of the tandem pore K(+) channel family. J Biol Chem 275:9340-9347

  • ↵3. Rajan S, Wischmeyer E, Xin Liu G, Preisig-Muller R, Daut J, Karschin A, and Derst C (2000) TASK-3, a novel tandem pore domain acid-sensitive K+ channel—an extracellular histidine as pH sensor. J Biol Chem 275:16650-16657

  • ↵4. Mu D, Chen L, Zhang X, See LH, Koch CM, Yen C, Tong JJ, Spiegel L, Nguyen KC, Servoss A, et al. (2003) Genomic amplification and oncogenic properties of the KCNK9 potassium channel gene. Cancer Cell 3:297-302

  • ↵5. Pei L, Wiser O, Slavin A, Mu D, Powers S, Jan LY, and Hoey T (2003) Oncogenic potential of TASK3 (Kcnk9) depends on K+ channel function. Proc Natl Acad Sci USA 100:7803-7807

  • ↵6. Lauritzen I, Zanzouri M, Honoré E, Duprat F, Ehrengruber MU, Lazdunski M, and Patel AJ (2003) K+-dependent cerebellar granule neuron apoptosis: role of TASK leak K+ channels. J Biol Chem 278:32068-32076

  • ↵7. Rajan S, Preisig-Muller R, Wischmeyer E, Nehring R, Hanley PJ, Renigunta V, Musset B, Schlichthorl G, Derst C, Karschin A, et al. (2002) Interaction with 14-3-3 proteins promotes functional expression of the potassium channels TASK-1 and TASK-3. J Physiol 545:13-26

  • ↵8. O'Kelly I, Butler MH, Zilberberg N, and Goldstein SA (2002) Forward transport. 14-3-3binding overcomes retention in endoplasmic reticulum by dibasic signals. Cell 111:577-588

  • ↵9. Kang DW, Han JH, Talley EM, Bayliss DA, and Kim D (2004) Functional expression of TASK-1/TASK-3 heteromer in cerebellar granule neurons. J Physiol 554:64-77

  • ↵10. Czirjak G and Enyedi P (2003) Ruthenium red inhibits TASK-3 potassium channel by interconnecting glutamate 70 of the two subunits. Mol Pharmacol 63:646-652

  • ↵11. Vega-Saenz de Miera E, Lau DH, Zhadina M, Pountney D, Coetzee WA, and Rudy B (2001) KT3.2 and KT3.3, two novel human two-pore K(+) channels closely related to TASK-1. J Neurophysiol 86:130-142