Potassium channels play a role in many cellular processes including maintenance of the action potential, muscle contraction, hormone secretion, osmotic regulation, and ion flow. This gene encodes the K2P4.1 protein, one of the members of the superfamily of potassium channel proteins containing two pore-forming P domains. K2P4.1 homodimerizes and functions as an outwardly rectifying channel. It is expressed primarily in neural tissues and is stimulated by membrane stretch and polyunsaturated fatty acids.4
KCNK4 protein channels are also called TRAAK channels. TRAAK channels are found in mammalian neurons and are part of a protein family of weakly inward rectifying potassium channels. This subfamily of potassium channels is mechanically gated. The C-terminal of TRAAK has a charged cluster that is important in maintaining the mechanosensitive properties of the channel.5
TRAAK is only expressed in neuronal tissue, and can be found in the brain, spinal cord, and retina, which suggests that it has a function beyond mechanotransduction in terms of neuronal excitability.6 The highest levels of TRAAK expression are in the olfactory system, cerebral cortex, hippocampal formation, habenula, basal ganglia, and cerebellum.6 TRAAK channels are mechanically activated when there is a convex curvature in the membrane that alters the channel’s activity. TRAAK channels are thought to have a role in axonal pathfinding, growth cone motility, and neurite elongation, as well as possibly having a role in touch or pain detection.78
^Lesage F, Maingret F, Lazdunski M (May 2000). "Cloning and expression of human TRAAK, a polyunsaturated fatty acids-activated and mechano-sensitive K(+) channel". FEBS Lett471 (2–3): 137–40. doi:10.1016/S0014-5793(00)01388-0. PMID10767409.
^Goldstein SA, Bayliss DA, Kim D, Lesage F, Plant LD, Rajan S (Dec 2005). "International Union of Pharmacology. LV. Nomenclature and molecular relationships of two-P potassium channels". Pharmacol Rev57 (4): 527–40. doi:10.1124/pr.57.4.12. PMID16382106.
^Vandorpe DH, Morris CE (1992). "Stretch activation of the Aplysia S-channel". The Journal of membrane biology127 (3): 205–214. PMID1495087.
^Maingret F, Fosset M, Lesage F, Lazdunski M, Honoré E (1999). "TRAAK is a mammalian neuronal mechano-gated K+ channel". The Journal of Biological Chemistry274 (3): 1381–1387. PMID9880510.
Goldstein SA, Bockenhauer D, O'Kelly I, Zilberberg N (2001). "Potassium leak channels and the KCNK family of two-P-domain subunits". Nat. Rev. Neurosci.2 (3): 175–84. doi:10.1038/35058574. PMID11256078.
Chapman CG, Meadows HJ, Godden RJ et al. (2001). "Cloning, localisation and functional expression of a novel human, cerebellum specific, two pore domain potassium channel". Brain Res. Mol. Brain Res.82 (1–2): 74–83. doi:10.1016/S0169-328X(00)00183-2. PMID11042359.
Ozaita A, Vega-Saenz de Miera E (2003). "Cloning of two transcripts, HKT4.1a and HKT4.1b, from the human two-pore K+ channel gene KCNK4. Chromosomal localization, tissue distribution and functional expression". Brain Res. Mol. Brain Res.102 (1–2): 18–27. doi:10.1016/S0169-328X(02)00157-2. PMID12191490.