View source for Inward-rectifier potassium channel

{{Short description|Group of transmembrane proteins that passively transport potassium ions}}
{{Infobox protein family
| Symbol = IRK
| Name = Inward rectifier potassium channel
| image = TREK_PIP2.png
| width = 
| caption = crystal structure of an inward rectifier potassium channel
| Pfam = PF01007
| Pfam_clan = CL0030 
| InterPro = IPR013521
| SMART = 
| PROSITE = 
| MEROPS = 
| SCOP = 1n9p
| TCDB = 1.A.2
| OPM family = 8
| OPM protein = 3SPG
| CAZy = 
| CDD = 
}}

'''Inward-rectifier potassium channels''' ('''K<sub>ir</sub>''', '''IRK''') are a specific [[Lipid-gated_ion_channels|lipid-gated]] 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 | display-authors = 6 | 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 | s2cid = 11588492 | 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 | display-authors = 6 | 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 | s2cid = 12718513 }}</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 activated by phosphatidylinositol 4,5-bisphosphate ([[Phosphatidylinositol 4,5-bisphosphate|PIP<sub>2</sub>]]). The malfunction of the channels has been implicated in several diseases.<ref>{{cite journal | vauthors = Hansen SB | title = Lipid agonism: The PIP2 paradigm of ligand-gated ion channels | journal = Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids | volume = 1851 | issue = 5 | pages = 620–8 | date = May 2015 | pmid = 25633344 | pmc = 4540326 | doi = 10.1016/j.bbalip.2015.01.011 }}</ref><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 | doi = 10.1096/fasebj.13.14.1901 | doi-access = free | s2cid = 22205168 }}</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-oligomer|homo-]] or [[Hetero-oligomers|heterooligomers]] and each monomer possesses between 2 and 4 TMSs. In terms of function, these proteins transport [[potassium|potassium (K<sup>+</sup>)]], with a greater tendency for K<sup>+</sup> uptake than K<sup>+</sup> export.<ref name="tcdb.org"/> The process of inward-rectification was discovered by [[Denis Noble]] in cardiac muscle cells in 1960s<ref>{{Cite journal |last=Noble |first=Denis |date=December 1965 |title=Electrical properties of cardiac muscle attributable to inward going (anomalous) rectification |url=https://onlinelibrary.wiley.com/doi/10.1002/jcp.1030660520 |journal=Journal of Cellular and Comparative Physiology |language=en |volume=66 |issue=S2 |pages=127–135 |doi=10.1002/jcp.1030660520 |issn=0095-9898|url-access=subscription }}</ref> 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 | pmc = 1348790 | doi = 10.1113/jphysiol.1970.sp009140 }}</ref>

==Overview of inward rectification==
[[File:Inward-rectification.png|thumb|right|400px|'''Figure 1.''' [[Patch clamp#Whole-cell recording or whole-cell patch|Whole-cell current recordings]] of K<sub>ir</sub>2 inwardly-rectifying potassium channels expressed in an [[HEK cell|HEK293 cell]]. (This is a strongly inwardly rectifying current. Downward deflections are inward currents, upward deflections outward currents, and the x-axis is time in seconds.) There are 13 responses superimposed in this image. The bottom-most trace is [[ampere|current]] elicited by a voltage step to -60[[volt|mV]], and the top-most to +60mV, relative to the [[resting potential]], which is close to the K<sup>+</sup> [[reversal potential]] in this experimental system. Other traces are in 10mV increments between the two.]]

A channel that is "inwardly-rectifying" is one that passes current (positive charge) more easily in the inward direction (into the cell) than in the outward direction (out of the cell). It is thought that this current may play an important role in regulating neuronal activity, by helping to stabilize the [[resting membrane potential]] of the cell.

By convention, inward current (positive charge moving into the cell) is displayed in [[voltage clamp]] as a downward deflection, while an outward current (positive charge moving out of the cell) is shown as an upward deflection. At membrane potentials negative to potassium's [[reversal potential]], inwardly rectifying K<sup>+</sup> channels support the flow of positively charged K<sup>+</sup> ions into the cell, pushing the membrane potential back to the resting potential. This can be seen in figure 1: when the membrane potential is clamped negative to the channel's resting potential (e.g. -60 mV), inward current flows (i.e. positive charge flows into the cell). However, when the membrane potential is set positive to the channel's resting potential (e.g. +60 mV), these channels pass very little current. Simply put, this channel passes much more current in the inward direction than the outward one, at its operating voltage range. These channels are not perfect rectifiers, as they can pass some outward current in the voltage range up to about 30 mV above resting potential.

These channels differ from the potassium channels that are typically responsible for repolarizing a cell following an [[action potential]], such as the [[Voltage-gated potassium channel#Delayed rectifier|delayed rectifier]] and [[Voltage-gated potassium channel#A-type potassium channel|A-type]] potassium channels. Those more "typical" potassium channels preferentially carry outward (rather than inward) potassium currents at depolarized membrane potentials, and may be thought of as "outwardly rectifying." When first discovered, inward rectification was named "anomalous rectification" to distinguish it from outward potassium currents.<ref>[[Bertil Hille]] (2001). ''Ion Channels of Excitable Membranes'' 3rd ed. (Sinauer: Sunderland, MA), p. 151. {{ISBN|0-87893-321-2}}.</ref>

Inward rectifiers also differ from [[tandem pore domain potassium channel]]s, which are largely responsible for "leak" K<sup>+</sup> currents.<ref>Hille, p. 155.</ref> Some inward rectifiers, termed "weak inward rectifiers", carry measurable outward K<sup>+</sup> currents at voltages positive to the K<sup>+</sup> reversal potential (corresponding to, but larger than, the small currents above the 0 nA line in figure 1). They, along with the "leak" channels, establish the resting membrane potential of the cell. Other inwardly rectifying channels, termed "strong inward rectifiers," carry very little outward current at all, and are mainly active at voltages negative to the K<sup>+</sup> reversal potential, where they carry inward current (the much larger currents below the 0 nA line in figure 1).<ref>Hille, p. 153.</ref>

==Mechanism of inward rectification==
The phenomenon of inward rectification of K<sub>ir</sub> channels is the result of high-affinity block by endogenous [[polyamine]]s, namely [[spermine]], as well as [[magnesium]] ions, that plug the [[potassium channel#Structure|channel pore]] at positive potentials, resulting in a decrease in outward currents. This voltage-dependent block by polyamines results in efficient conduction of current only in the inward direction. While the principal idea of polyamine block is understood, the specific mechanisms are still controversial.<ref>{{cite journal | vauthors = Lopatin AN, Makhina EN, Nichols CG | title = The mechanism of inward rectification of potassium channels: "long-pore plugging" by cytoplasmic polyamines | journal = The Journal of General Physiology | volume = 106 | issue = 5 | pages = 923–55 | date = November 1995 | pmid = 8648298 | pmc = 2229292 | doi = 10.1085/jgp.106.5.923 }}</ref>

==Activation by PIP<sub>2</sub>==
All K<sub>ir</sub> channels require [[phosphatidylinositol 4,5-bisphosphate]] (PIP<sub>2</sub>) for activation.<ref name="pmid18411329">{{cite journal | vauthors = Tucker SJ, Baukrowitz T | title = How highly charged anionic lipids bind and regulate ion channels | journal = The Journal of General Physiology | volume = 131 | issue = 5 | pages = 431–8 | date = May 2008 | pmid = 18411329 | pmc = 2346576 | doi = 10.1085/jgp.200709936 }}</ref> PIP<sub>2</sub> binds to and directly activates K<sub>ir</sub> 2.2 with agonist-like properties.<ref>{{cite journal | vauthors = Hansen SB, Tao X, MacKinnon R | title = Structural basis of PIP2 activation of the classical inward rectifier K+ channel Kir2.2 | journal = Nature | volume = 477 | issue = 7365 | pages = 495–8 | date = August 2011 | pmid = 21874019 | pmc = 3324908 | doi = 10.1038/nature10370 | bibcode = 2011Natur.477..495H }}</ref> In this regard K<sub>ir</sub> channels are PIP<sub>2</sub> [[ligand-gated ion channels]].

==Role==
K<sub>ir</sub> channels are found in multiple cell types, including [[macrophages]], [[cardiac]] and [[kidney]] cells, [[leukocytes]], [[neurons]], and [[endothelial cells]]. By mediating a small [[depolarization|depolarizing]] K<sup>+</sup> current at negative membrane potentials, they help establish resting membrane potential, and in the case of the [[G protein-coupled inwardly-rectifying potassium channel|K<sub>ir</sub>3]] group, they help mediate inhibitory [[neurotransmitter]] responses, but their roles in cellular physiology vary across cell types:

{| class="wikitable"
!'''Location'''!!'''Function'''
 |-
 | [[Cardiac muscle cell|cardiac myocytes]]  || K<sub>ir</sub> channels close upon depolarization, slowing membrane repolarization and helping maintain a more prolonged [[cardiac action potential]]. This type of inward-rectifier channel is distinct from [[Voltage-gated potassium channel|delayed rectifier K<sup>+</sup> channels]], which help repolarize nerve and muscle cells after [[action potential]]s; and [[Tandem pore domain potassium channel|potassium leak channels]], which provide much of the basis for the [[Resting potential|resting membrane potential]].
 |-
 | [[endothelial cell]]s || K<sub>ir</sub> channels are involved in regulation of [[nitric oxide synthase]].
 |-
 | [[kidneys]]  || K<sub>ir</sub> export surplus potassium into collecting tubules for removal in the urine, or alternatively may be involved in the reuptake of potassium back into the body.
 |-
 | [[neurons]] and in heart cells || [[G protein-coupled inwardly-rectifying potassium channel|G-protein activated IRKs (K<sub>ir</sub>3)]] are important regulators, modulated by neurotransmitters. A mutation in the [[KCNJ6|GIRK2]] channel leads to the weaver mouse mutation. "Weaver" mutant mice are ataxic and display a neuroinflammation-mediated degeneration of their dopaminergic neurons.<ref>{{cite journal | vauthors = Peng J, Xie L, Stevenson FF, Melov S, Di Monte DA, Andersen JK | title = Nigrostriatal dopaminergic neurodegeneration in the weaver mouse is mediated via neuroinflammation and alleviated by minocycline administration | journal = The Journal of Neuroscience | volume = 26 | issue = 45 | pages = 11644–51 | date = November 2006 | pmid = 17093086 | pmc = 6674792 | doi = 10.1523/JNEUROSCI.3447-06.2006 }}</ref> Relative to non-ataxic controls, Weaver mutants have deficits in motor coordination and changes in regional brain metabolism.<ref>{{cite journal | vauthors = Strazielle C, Deiss V, Naudon L, Raisman-Vozari R, Lalonde R | title = Regional brain variations of cytochrome oxidase activity and motor coordination in Girk2(Wv) (Weaver) mutant mice | journal = Neuroscience | volume = 142 | issue = 2 | pages = 437–49 | date = October 2006 | pmid = 16844307 | doi = 10.1016/j.neuroscience.2006.06.011 | s2cid = 33064439 }}</ref> Weaver mice have been examined in labs interested in neural development and disease for over 30 years.
 |-
 |  pancreatic [[beta cell]]s || [[ATP-sensitive potassium channel|K<sub>ATP</sub> channels]] (composed of [[Kir6.2|K<sub>ir</sub>6.2]] and [[sulfonylurea receptor|SUR1]] subunits) control insulin release.
|}

== Regulation ==
Voltage-dependence may be regulated by external K<sup>+</sup>, by internal Mg<sup>2+</sup>, by internal [[Adenosine triphosphate|ATP]] and/or by [[G protein|G-proteins]]. The P domains of IRK channels exhibit limited sequence similarity to those of the VIC family. Inward rectifiers play a role in setting cellular membrane potentials, and closing of these channels upon depolarization permits the occurrence of long duration action potentials with a plateau phase. Inward rectifiers lack the intrinsic voltage sensing helices found in many VIC family channels. In a few cases, those of Kir1.1a, Kir6.1 and Kir6.2, for example, direct interaction with a member of the ABC superfamily has been proposed to confer unique functional and regulatory properties to the heteromeric complex, including sensitivity to ATP. These ATP-sensitive channels are found in many body tissues. They render channel activity responsive to the cytoplasmic ATP/ADP ratio (increased ATP/ADP closes the channel). The human SUR1 and SUR2 [[sulfonylurea]] receptors (spQ09428 and Q15527, respectively) are the ABC proteins that regulate both the Kir6.1 and Kir6.2 channels in response to ATP, and CFTR ([http://www.tcdb.org/search/result.php?tc=3.A.1.208.4 TC #3.A.1.208.4]) may regulate Kir1.1a.<ref>{{cite patent |country= WO |number= 0190360 |status= application |title= Isolated human transporter proteins, nucleic acid molecules encoding human transporter proteins, and uses thereof |pubdate= 29 November 2001 |gdate= |fdate= |pridate= |inventor= Wei MH, Chaturvedi K, Guegler K, Webster M, Ketchum KA, Di Francesco V, Beasley E  |assign1= Apperla Corporation }}</ref>

== Structure ==
The crystal structure<ref>{{cite journal | vauthors = Kuo A, Gulbis JM, Antcliff JF, Rahman T, Lowe ED, Zimmer J, Cuthbertson J, Ashcroft FM, Ezaki T, Doyle DA | display-authors = 6 | title = Crystal structure of the potassium channel KirBac1.1 in the closed state | journal = Science | volume = 300 | issue = 5627 | pages = 1922–6 | date = June 2003 | pmid = 12738871 | doi = 10.1126/science.1085028 | bibcode = 2003Sci...300.1922K | s2cid = 2703162 | doi-access = free }}</ref> and function<ref name=":0">{{cite journal | vauthors = Enkvetchakul D, Bhattacharyya J, Jeliazkova I, Groesbeck DK, Cukras CA, Nichols CG | title = Functional characterization of a prokaryotic Kir channel | journal = The Journal of Biological Chemistry | volume = 279 | issue = 45 | pages = 47076–80 | date = November 2004 | pmid = 15448150 | doi = 10.1074/jbc.C400417200 | pmc = 8629170 | doi-access = free }}</ref> of bacterial members of the IRK-C family have been determined. KirBac1.1, from ''[[Burkholderia pseudomallei]]'', is 333 amino acyl residues (aas) long with two N-terminal TMSs flanking a P-loop (residues 1-150), and the C-terminal half of the protein is hydrophilic. It transports monovalent cations with the selectivity: K ≈ Rb ≈ Cs ≫ Li ≈ Na ≈ NMGM (protonated [[meglumine|''N''-methyl-<small>D</small>-glucamine]]). Activity is inhibited by Ba<sup>2+</sup>, Ca<sup>2+</sup>, and low pH.<ref name=":0" />

==Classification==
There are seven subfamilies of K<sub>ir</sub> channels, denoted as K<sub>ir</sub>1 – K<sub>ir</sub>7.<ref name="Kubo"/> Each subfamily has multiple members (i.e. K<sub>ir</sub>2.1, K<sub>ir</sub>2.2, K<sub>ir</sub>2.3, etc.) that have nearly identical amino acid sequences across known mammalian species.

K<sub>ir</sub> channels are formed from as [[homotetrameric]] membrane proteins. Each of the four identical protein subunits is composed of two membrane-spanning [[alpha helix|alpha helices]] (M1 and M2). Heterotetramers can form between members of the same subfamily (i.e. K<sub>ir</sub>2.1 and K<sub>ir</sub>2.3) when the channels are overexpressed.

===Diversity===

{| class="sortable wikitable"
!'''Gene'''!!'''Protein'''!!'''Aliases'''!!'''Associated subunits'''
 |-
 | {{Gene|KCNJ1}} || [[ROMK|K<sub>ir</sub>1.1]] || ROMK1 || [[Sodium-hydrogen exchange regulatory cofactor 2|NHERF2]]
 |-
 | {{Gene|KCNJ2}} || [[KCNJ2|K<sub>ir</sub>2.1]] || IRK1 || K<sub>ir</sub>2.2, K<sub>ir</sub>4.1, [[DLG4|PSD-95]], [[DLG1|SAP97]], [[AKAP5|AKAP79]]
 |-
 | {{Gene|KCNJ12}} || [[KCNJ12|K<sub>ir</sub>2.2]] || IRK2 || K<sub>ir</sub>2.1 and K<sub>ir</sub>2.3 to form heteromeric channel, auxiliary subunit: SAP97, [[LIN7A|Veli-1]], [[LIN7C|Veli-3]], PSD-95
 |-
 | {{Gene|KCNJ4}} || [[KCNJ4|K<sub>ir</sub>2.3]] || IRK3 || K<sub>ir</sub>2.1 and K<sub>ir</sub>2.3 to form heteromeric channel, PSD-95, [[DLG2|Chapsyn-110]]/PSD-93
 |-
 | {{Gene|KCNJ14}} || [[KCNJ14|K<sub>ir</sub>2.4]] || IRK4 || K<sub>ir</sub>2.1 to form heteromeric channel
 |-
 | {{Gene|KCNJ3}} || [[KCNJ3|K<sub>ir</sub>3.1]] || GIRK1, KGA || K<sub>ir</sub>3.2, K<sub>ir</sub>3.4, K<sub>ir</sub>3.5, K<sub>ir</sub>3.1 is not functional by itself
 |-
 | {{Gene|KCNJ6}} ||  [[KCNJ6|K<sub>ir</sub>3.2]] || GIRK2 || K<sub>ir</sub>3.1, K<sub>ir</sub>3.3, K<sub>ir</sub>3.4 to form heteromeric channel
 |-
 | {{Gene|KCNJ9}} || [[KCNJ9|K<sub>ir</sub>3.3]] || GIRK3 || K<sub>ir</sub>3.1, K<sub>ir</sub>3.2 to form heteromeric channel
 |-
 | {{Gene|KCNJ5}} || [[KCNJ5|K<sub>ir</sub>3.4]] ||  GIRK4 || K<sub>ir</sub>3.1, K<sub>ir</sub>3.2, K<sub>ir</sub>3.3
 |-
 | {{Gene|KCNJ10}} || [[KCNJ10|K<sub>ir</sub>4.1]] || K<sub>ir</sub>1.2 || K<sub>ir</sub>4.2, K<sub>ir</sub>5.1, and K<sub>ir</sub>2.1 to form heteromeric channels
 |-
 | {{Gene|KCNJ15}} || [[KCNJ15|K<sub>ir</sub>4.2]] || K<sub>ir</sub>1.3 ||
 |-
 | {{Gene|KCNJ16}} || [[KCNJ16|K<sub>ir</sub>5.1]] || BIR 9 ||
 |-
 | {{Gene|KCNJ8}} || [[KCNJ8|K<sub>ir</sub>6.1]] || [[ATP-sensitive potassium channel|K<sub>ATP</sub>]] || [[ABCC9|SUR2B]]
 |-
 | {{Gene|KCNJ11}} || [[Kir6.2|K<sub>ir</sub>6.2]] || [[ATP-sensitive potassium channel|K<sub>ATP</sub>]] || [[ABCC8|SUR1]], [[ABCC9|SUR2A]], and [[ABCC9|SUR2B]]
 |-
 | {{Gene|KCNJ13}} || [[KCNJ13|K<sub>ir</sub>7.1]] || K<sub>ir</sub>1.4 ||
|}

==Diseases related to K<sub>ir</sub> channels==
*''[[Persistent hyperinsulinemic hypoglycemia of infancy]]'' is related to autosomal recessive mutations in K<sub>ir</sub>6.2. Certain mutations of this gene diminish the channel's ability to regulate insulin secretion, leading to [[hypoglycemia]].
*''[[Bartter's syndrome]]'' can be caused by mutations in K<sub>ir</sub> channels. This condition is characterized by the inability of kidneys to recycle potassium, causing [[low levels of potassium]] in the body.
*''[[Andersen's syndrome]]'' is a rare condition caused by multiple mutations of K<sub>ir</sub>2.1. Depending on the mutation, it can be dominant or recessive. It is characterized by [[periodic paralysis]], [[cardiac arrhythmias]] and [[dysmorphic]] features. (See also [[KCNJ2]])
*''[[Barium poisoning]]'' is likely due to its ability to block K<sub>ir</sub> channels.
*''[[Atherosclerosis]] (heart disease)'' may be related to K<sub>ir</sub> channels. The loss of K<sub>ir</sub> currents in endothelial cells is one of the first known indicators of atherogenesis (the beginning of heart disease).
*''[[Thyrotoxic hypokalaemic periodic paralysis]]'' has been linked to altered K<sub>ir</sub>2.6 function.<ref>{{cite journal | vauthors = Ryan DP, da Silva MR, Soong TW, Fontaine B, Donaldson MR, Kung AW, Jongjaroenprasert W, Liang MC, Khoo DH, Cheah JS, Ho SC, Bernstein HS, Maciel RM, Brown RH, Ptácek LJ | display-authors = 6 | title = Mutations in potassium channel Kir2.6 cause susceptibility to thyrotoxic hypokalemic periodic paralysis | journal = Cell | volume = 140 | issue = 1 | pages = 88–98 | date = January 2010 | pmid = 20074522 | pmc = 2885139 | doi = 10.1016/j.cell.2009.12.024 }}</ref>
*''[[EAST/SeSAME syndrome]]'' is caused by mutations in KCNJ10.<ref>{{cite journal | vauthors = Bockenhauer D, Feather S, Stanescu HC, Bandulik S, Zdebik AA, Reichold M, Tobin J, Lieberer E, Sterner C, Landoure G, Arora R, Sirimanna T, Thompson D, Cross JH, van't Hoff W, Al Masri O, Tullus K, Yeung S, Anikster Y, Klootwijk E, Hubank M, Dillon MJ, Heitzmann D, Arcos-Burgos M, Knepper MA, Dobbie A, Gahl WA, Warth R, Sheridan E, Kleta R | display-authors = 6 | title = Epilepsy, ataxia, sensorineural deafness, tubulopathy, and KCNJ10 mutations | journal = The New England Journal of Medicine | volume = 360 | issue = 19 | pages = 1960–70 | date = May 2009 | pmid = 19420365 | pmc = 3398803 | doi = 10.1056/NEJMoa0810276 }}</ref>

== See also ==
* [[G protein-coupled inwardly-rectifying potassium channel]]
* [[hERG]]
* [[Transporter Classification Database]]

== References ==
{{Reflist}}

== Further reading ==
{{refbegin}}
* {{cite book | vauthors = Hille B | author-link1 = Bertil Hille | date = 2001 | title = Ion Channels of Excitable Membranes | edition = 3rd | publisher = Sinauer | location = Sunderland, MA | pages = 149–154 | isbn = 0-87893-321-2}}
{{refend}}

== External links ==
* {{MeshName|Inward+Rectifier+Potassium+Channels}}.
* {{cite web | url = http://www.iuphar-db.org/IC/FamilyMenuForward?familyId=17| title = Inwardly Recifying Potassium Channels | work = IUPHAR Database of Receptors and Ion Channels | publisher = International Union of Basic and Clinical Pharmacology }}
* {{UMichOPM|families|family|85}} - Spatial positions of inward rectifier potassium channels in membranes.

{{Ion channels|g3}}
{{channel blockers}}

{{DEFAULTSORT:Inward-Rectifier Potassium Ion Channel}}
[[Category:Potassium channels]]
[[Category:Electrophysiology]]
[[Category:Integral membrane proteins]]