Two-pore-domain potassium channel

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The two-pore-domain or tandem pore domain potassium channels are a family of 15 members that form what is known as "leak channels" which possess Goldman-Hodgkin-Katz (open) rectification. [1] These channels are regulated by several mechanisms including signaling lipids, oxygen tension, pH, mechanical stretch, and G-proteins .[ citation needed ] Their name is derived from the fact that the α subunits consist of four transmembrane segments, and each pair of transmembrane segments contains a pore loop between the two transmembrane segments. Thus, each subunit has two pore loops. As such, they structurally correspond to two inward-rectifier α subunits and thus form dimers in the membrane (whereas inward-rectifier α subunits form tetramers).

Contents

Each single channel does not have two pores; the name of the channel comes from the fact that each subunit has two P (pore) domains in its primary sequence. [2] To quote Rang and Dale (2015), "The nomenclature is misleading, especially when they are incorrectly referred to as two-pore channels". [3]

Below is a list of the 15 known two-pore-domain human potassium channels: [1]

GeneChannel [4] FamilyAliases
KCNK1 K2p1.1 TWIK [5] [6] TWIK-1
KCNK2 K2p2.1 TREK [5] [6] TREK-1
KCNK3 K2p3.1 TASK [5] [6] TASK-1
KCNK4 K2p4.1 TREK [5] [6] TRAAK [7]
KCNK5 K2p5.1 TASK [5] [6] TASK-2 [8]
KCNK6 K2p6.1 TWIK [5] [6] TWIK-2
KCNK7 K2p7.1 TWIK [5] [6]
KCNK9 K2p9.1 TASK [5] [6] TASK-3
KCNK10 K2p10.1 TREK [5] [6] TREK-2
KCNK12 K2p12.1 THIKTHIK-2
KCNK13 K2p13.1 THIKTHIK-1
KCNK15 K2p15.1 TASK [5] [6] TASK-5
KCNK16 K2p16.1 TALK [5] [6] TALK-1
KCNK17 K2p17.1 TALK [5] [6] TALK-2, TASK-4
KCNK18 K2p18.1 TRIK, TRESK [5] [6] [9] [10]

See also

Related Research Articles

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Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane, controlling the flow of ions across secretory and epithelial cells, and regulating cell volume. Ion channels are present in the membranes of all cells. Ion channels are one of the two classes of ionophoric proteins, the other being ion transporters.

Potassium channel Ion channel that selectively passes K+

Potassium channels are the most widely distributed type of ion channel and are found in virtually all living organisms. They form potassium-selective pores that span cell membranes. Potassium channels are found in most cell types and control a wide variety of cell functions.

Voltage-gated ion channel Type of ion channel transmembrane protein

Voltage-gated ion channels are a class of transmembrane proteins that form ion channels that are activated by changes in the electrical membrane potential near the channel. The membrane potential alters the conformation of the channel proteins, regulating their opening and closing. Cell membranes are generally impermeable to ions, thus they must diffuse through the membrane through transmembrane protein channels. They have a crucial role in excitable cells such as neuronal and muscle tissues, allowing a rapid and co-ordinated depolarization in response to triggering voltage change. Found along the axon and at the synapse, voltage-gated ion channels directionally propagate electrical signals. Voltage-gated ion-channels are usually ion-specific, and channels specific to sodium (Na+), potassium (K+), calcium (Ca2+), and chloride (Cl−) ions have been identified. The opening and closing of the channels are triggered by changing ion concentration, and hence charge gradient, between the sides of the cell membrane.

Inward-rectifier potassium channel Group of transmembrane proteins that passively transport potassium ions

Inward-rectifier potassium channels (Kir, IRK) are a specific lipid-gated subset of potassium channels. To date, seven subfamilies have been identified in various mammalian cell types, plants, and bacteria. They are activated by phosphatidylinositol 4,5-bisphosphate (PIP2). The malfunction of the channels has been implicated in several diseases. IRK channels possess a pore domain, homologous to that of voltage-gated ion channels, and flanking transmembrane segments (TMSs). They may exist in the membrane as homo- or heterooligomers and each monomer possesses between 2 and 4 TMSs. In terms of function, these proteins transport potassium (K+), with a greater tendency for K+ uptake than K+ export. The process of inward-rectification was discovered by Denis Noble in cardiac muscle cells in 1960s and by Richard Adrian and Alan Hodgkin in 1970 in skeletal muscle cells.

Voltage-gated potassium channel Class of transport proteins

Voltage-gated potassium channels (VGKCs) are transmembrane channels specific for potassium and sensitive to voltage changes in the cell's membrane potential. During action potentials, they play a crucial role in returning the depolarized cell to a resting state.

KCNB1

Potassium voltage-gated channel, Shab-related subfamily, member 1, also known as KCNB1 or Kv2.1, is a protein that, in humans, is encoded by the KCNB1 gene.

KCNK2

Potassium channel subfamily K member 2 is a protein that in humans is encoded by the KCNK2 gene.

KCNK3

Potassium channel subfamily K member 3 is a protein that in humans is encoded by the KCNK3 gene.

KCNK1

Potassium channel subfamily K member 1 is a protein that in humans is encoded by the KCNK1 gene.

KCNK9 Protein-coding gene in the species Homo sapiens

Potassium channel subfamily K member 9 is a protein that in humans is encoded by the KCNK9 gene.

KCNK4

Potassium channel subfamily K member 4 is a protein that in humans is encoded by the KCNK4 gene. KCNK4 protein channels are also called TRAAK channels.

KCNK6 Protein-coding gene in humans

Potassium channel subfamily K member 6 is a protein that in humans is encoded by the KCNK6 gene.

KCNK5

Potassium channel subfamily K member 5 is a protein that in humans is encoded by the KCNK5 gene.

KCNK7

Potassium channel, subfamily K, member 7, also known as KCNK7 or K2P7.1 is a protein which is encoded in humans by the KCNK7 gene. K2P7.1 is a potassium channel containing two pore-forming P domains. Multiple transcript variants encoding different isoforms have been found for this gene.

KCNK10

Potassium channel, subfamily K, member 10, also known as KCNK10 is a human gene. The protein encoded by this gene, K2P10.1, is a potassium channel containing two pore-forming P domains.

KCNK13

Potassium channel, subfamily K, member 13, also known as KCNK13 is a human gene. The protein encoded by this gene, K2P13.1 is a potassium channel containing two pore-forming P domains.

KCNK16

Potassium channel subfamily K member 16 is a protein that in humans is encoded by the KCNK16 gene. The protein encoded by this gene, K2P16.1, is a potassium channel containing two pore-forming P domains.

KCNK18

Potassium channel subfamily K member 18 (KCNK18), also known as TWIK-related spinal cord potassium channel (TRESK) or K2P18.1 is a protein that in humans is encoded by the KCNK18 gene. K2P18.1 is a potassium channel containing two pore-forming P domains.

A potassium channel opener is a type of drug which facilitates ion transmission through potassium channels.

Lq2

Lq2 is a component of the venom of the scorpion Leiurus quinquestriatus. It blocks various potassium channels, among others the inward-rectifier potassium ion channel ROMK1.

References

  1. 1 2 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". Pharmacological Reviews. 57 (4): 527–40. doi:10.1124/pr.57.4.12. PMID   16382106. S2CID   7356601.
  2. ↑ "Two P domain potassium channels". Guide to Pharmacology . Retrieved 2019-05-28.
  3. ↑ Rang, HP (2003). Pharmacology (8 ed.). Edinburgh: Churchill Livingstone. p. 59. ISBN   978-0-443-07145-4.
  4. ↑ Gutman GA, Chandy KG, Adelman JP, Aiyar J, Bayliss DA, Clapham DE, et al. (Dec 2003). "International Union of Pharmacology. XLI. Compendium of voltage-gated ion channels: potassium channels". Pharmacological Reviews. 55 (4): 583–6. doi:10.1124/pr.55.4.9. PMID   14657415. S2CID   34963430.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 13 Enyedi P, Czirják G (Apr 2010). "Molecular background of leak K+ currents: two-pore domain potassium channels". Physiological Reviews. 90 (2): 559–605. doi:10.1152/physrev.00029.2009. PMID   20393194.
  6. 1 2 3 4 5 6 7 8 9 10 11 12 13 Lotshaw DP (2007). "Biophysical, pharmacological, and functional characteristics of cloned and native mammalian two-pore domain K+ channels". Cell Biochemistry and Biophysics . 47 (2): 209–56. doi:10.1007/s12013-007-0007-8. PMID   17652773. S2CID   12759521.
  7. ↑ Fink M, Lesage F, Duprat F, Heurteaux C, Reyes R, Fosset M, Lazdunski M (Jun 1998). "A neuronal two P domain K+ channel stimulated by arachidonic acid and polyunsaturated fatty acids". The EMBO Journal. 17 (12): 3297–308. doi:10.1093/emboj/17.12.3297. PMC   1170668 . PMID   9628867.
  8. ↑ Goldstein SA, Bockenhauer D, O'Kelly I, Zilberberg N (Mar 2001). "Potassium leak channels and the KCNK family of two-P-domain subunits". Nature Reviews. Neuroscience. 2 (3): 175–84. doi:10.1038/35058574. PMID   11256078. S2CID   9682396.
  9. ↑ Sano Y, Inamura K, Miyake A, Mochizuki S, Kitada C, Yokoi H, Nozawa K, Okada H, Matsushime H, Furuichi K (Jul 2003). "A novel two-pore domain K+ channel, TRESK, is localized in the spinal cord". The Journal of Biological Chemistry. 278 (30): 27406–12. doi: 10.1074/jbc.M206810200 . PMID   12754259.
  10. ↑ Czirják G, Tóth ZE, Enyedi P (Apr 2004). "The two-pore domain K+ channel, TRESK, is activated by the cytoplasmic calcium signal through calcineurin". The Journal of Biological Chemistry. 279 (18): 18550–8. doi: 10.1074/jbc.M312229200 . PMID   14981085.
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