View source for KCNJ15

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{{Infobox_gene}}

'''Potassium inwardly-rectifying channel, subfamily J, member 15''', also known as '''KCNJ15''' is a human [[gene]], which encodes the '''K<sub>ir</sub>4.2''' [[protein]].<ref name="entrez">{{cite web | title = Entrez Gene: KCNJ15 potassium inwardly-rectifying channel, subfamily J, member 15| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3772| accessdate = }}</ref>

== Function ==

Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. '''K<sub>ir</sub>4.2''' is an integral membrane protein and inward-rectifier type potassium channel. '''K<sub>ir</sub>4.2''' has a greater tendency to allow potassium to flow into a cell rather than out of a cell. Three transcript variants encoding the same protein have been found for this gene.<ref name="entrez"/>

The existing literature describing KCNJ15 and K<sub>ir</sub>4.2 is sparse. In spite of some initial channel nomenclature confusion, in which the gene was referred to as Kir1.3<ref name="Pearson et al. 1999">{{cite journal |vauthors=Pearson WL, Dourado M, Schreiber M, Salkoff L, Nichols CG |title=Expression of a functional Kir4 family inward rectifier K+ channel from a gene cloned from mouse liver |journal=J. Physiol. |volume=514 ( Pt 3) |issue= 3|pages=639–653 |year=1999 |pmid=9882736 |doi=10.1111/j.1469-7793.1999.639ad.x |pmc=2269105}}</ref> the channel was first cloned from human [[kidney]] by Shuck and coworkers in 1997.<ref name="Shuck et al. 1997">{{cite journal |vauthors=Shuck ME, Piser TM, Bock JH, Slightom JL, Lee KS, Bienkowski MJ |title=Cloning and characterization of two K+ inward rectifier (Kir) 1.1 potassium channel homologs from human kidney (Kir1.2 and Kir1.3) |journal=J. Biol. Chem. |volume=272 |issue=1 |pages=586–593 |year=1997 |pmid=8995301 |doi=10.1074/jbc.272.1.586}}</ref> Shortly thereafter it was shown that mutation of an extracellular [[lysine]] residue resulted in 6-fold increase in K<sup>+</sup> current.<ref name="Derst et al. 1998">{{cite journal |author=Derst C |title=A hyperprostaglandin E syndrome mutation in Kir1.1 (renal outer medullary potassium) channels reveals a crucial residue for channel function in Kir1.3 channels |journal=J. Biol. Chem. |volume=273 |issue=37 |pages=23884–23891 |year=1998 |pmid=9727001 |doi=10.1074/jbc.273.37.23884 |name-list-format=vanc|author2=Wischmeyer E |author3=Preisig-Müller R |display-authors=3 |last4=Spauschus |first4=A |last5=Konrad |first5=M |last6=Hensen |first6=P |last7=Jeck |first7=N |last8=Seyberth |first8=HW |last9=Daut |first9=J}}</ref> Two years later, in 1999, voltage clamp measurements in [[xenopus]] [[oocytes]] found that intracellular acidification decreased the potassium current of K<sub>ir</sub>4.2. Also activation of protein kinase C decreased the current although in a non-reversible fashion. Furthermore, it was found that coexpression with related potassium channel [[KCNJ16|K<sub>ir</sub>5.1]], changed these results somewhat, which the authors concluded was likely to be a result of heterodimerization.<ref name="Pearson et al. 1999" /> Further voltage clamp investigations found the exact pH sensitivity (pK<sub>a</sub> = 7.1), open probability (high) and conductance of ~25 pS.<ref name="Pessia et al. 2001">{{cite journal |vauthors=Pessia M, Imbrici P, D'Adamo MC, Salvatore L, Tucker SJ |title=Differential pH sensitivity of Kir4.1 and Kir4.2 potassium channels and their modulation by heteropolymerisation with Kir5.1 |journal=J. Physiol. |volume=532 |issue=Pt 2 |pages=359–367 |year=2001 |pmid=11306656 |doi=10.1111/j.1469-7793.2001.0359f.x |pmc=2278540}}</ref> In 2007 the channel was found to interact with the [[Calcium-sensing receptor]] in human kidney, using a yeast-two-hybrid system. This co-localization was verified at the protein level using both [[immunofluorescence]] techniques and [[immunoprecipitation|coimmunoprecipitation]] of K<sub>ir</sub>4.2 and the [[Calcium-sensing receptor]].<ref name="Huang et al. 2007">{{cite journal |author=Huang C |title=Interaction of the Ca2+-sensing receptor with the inwardly rectifying potassium channels Kir4.1 and Kir4.2 results in inhibition of channel function |journal=Am. J. Physiol. Renal Physiol. |volume=292 |issue=3 |pages=F1073–F1081 |year=2007 |pmid=17122384 |doi=10.1152/ajprenal.00269.2006 |name-list-format=vanc|author2=Sindic A |author3=Hill CE |display-authors=3 |last4=Hujer |first4=K. M. |last5=Chan |first5=K. W. |last6=Sassen |first6=M. |last7=Wu |first7=Z. |last8=Kurachi |first8=Y. |last9=Nielsen |first9=S.}}</ref> Also a mutational study of K<sub>ir</sub>4.2 has demonstrated that removal of a c-terminal [[tyrosine]] increased the K<sup>+</sup> current more than 10-fold.<ref name="Pearson et al. 2007">{{cite journal |vauthors=Pearson WL, Skatchkov SN, Eaton MJ, Nichols CG |title=C-terminal determinants of Kir4.2 channel expression |journal=J. Membr. Biol. |volume=213 |issue=3 |pages=187–193 |year=2006 |pmid=17468958 |doi=10.1007/s00232-006-0058-6}}</ref> Because the channel has a very high open probability, the authors of this last article conclude that this increase is mediated by increased trafficking of the protein to the membrane and not increased single-channel conductance. This same line of reasoning is applicable to the initial work of Derst and coworkers.<ref name="Derst et al. 1998" />

==Interactions==
KCNJ15 has been shown to [[Protein-protein interaction|interact]] with [[Interleukin 16]].<ref name=pmid10479680>{{cite journal |last=Kurschner |first=C |authorlink= |last2=Yuzaki |first2=M |date=Sep 1999|title=Neuronal interleukin-16 (NIL-16): a dual function PDZ domain protein |journal=J. Neurosci. |volume=19 |issue=18 |pages=7770–80 | pmid = 10479680}}</ref>

==See also==
* [[Inward-rectifier potassium ion channel]]

==References==
{{reflist}}

{{NLM content}}
{{Membrane proteins}}
{{Ion channels|g3}}

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[[Category:Ion channels]]