Inward-rectifier potassium channel: Difference between revisions

'''Inward-rectifier potassium channels''' ('''K_ir''', '''IRK''') are a specific subset of [[potassium channel]]s. To date, seven subfamilies have been identified in various mammalian cell types,<ref name="Kubo">{{cite journal | vauthors = Kubo Y, Adelman JP, Clapham DE, Jan LY, Karschin A, Kurachi Y, Lazdunski M, Nichols CG, Seino S, Vandenberg CA | title = International Union of Pharmacology. LIV. Nomenclature and Molecular Relationships of Inwardly Rectifying Potassium Channels | journal = Pharmacological Reviews | volume = 57 | issue = 4 | pages = 509–26 | date = December 2005 | pmid = 16382105 | doi = 10.1124/pr.57.4.11 | authorlink8 = Colin Nichols }}</ref> plants,<ref name="pmid8582318">{{cite journal | vauthors = Hedrich R, Moran O, Conti F, Busch H, Becker D, Gambale F, Dreyer I, Küch A, Neuwinger K, Palme K | title = Inward rectifier potassium channels in plants differ from their animal counterparts in response to voltage and channel modulators | journal = European Biophysics Journal | volume = 24 | issue = 2 | pages = 107–15 | year = 1995 | pmid = 8582318 | doi = 10.1007/BF00211406 }}</ref> and bacteria.<ref name="tcdb.org">{{Cite web|url = http://www.tcdb.org/search/result.php?tc=1.A.2|title = 1.A.2 Inward Rectifier K Channel (IRK-C) Family|website = TCDB|access-date = 2016-04-09}}</ref> They are the targets of multiple toxins, and malfunction of the channels has been implicated in several diseases.<ref name="Abraham">{{cite journal | vauthors = Abraham MR, Jahangir A, Alekseev AE, Terzic A | title = Channelopathies of inwardly rectifying potassium channels | journal = FASEB Journal | volume = 13 | issue = 14 | pages = 1901–10 | date = November 1999 | pmid = 10544173 | url = http://www.fasebj.org/cgi/content/full/13/14/1901 | doi = 10.1096/fasebj.13.14.1901 }}</ref> IRK channels possess a pore domain, homologous to that of [[voltage-gated ion channel]]s, and flanking [[transmembrane domain|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|potassium (K⁺)]], with a greater tendency for K⁺ uptake than K⁺ export.<ref name="tcdb.org"/> The process of inward-rectification was discovered by [[Denis Noble]] in cardiac muscle cells in 1960s and by [[Richard Adrian, 2nd Baron Adrian|Richard Adrian]] and [[Alan Lloyd Hodgkin|Alan Hodgkin]] in 1970 in skeletal muscle cells.<ref>{{cite journal | vauthors = Adrian RH, Chandler WK, Hodgkin AL | title = Slow changes in potassium permeability in skeletal muscle | journal = The Journal of Physiology | volume = 208 | issue = 3 | pages = 645–68 | date = July 1970 | pmid = 5499788 | doi = 10.1113/jphysiol.1970.sp009140 | pmc = 1348790 }}</ref>