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== Function ==
== Function ==
[https://www.uniprot.org/uniprot/KCNJ6_MOUSE KCNJ6_MOUSE] This potassium channel is controlled by G proteins. It plays a role in granule cell differentiation, possibly via membrane hyperpolarization. Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium.
[https://www.uniprot.org/uniprot/KCNJ6_MOUSE KCNJ6_MOUSE] This potassium channel is controlled by G proteins. It plays a role in granule cell differentiation, possibly via membrane hyperpolarization. Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium.
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== Publication Abstract from PubMed ==
Ion channels gate at membrane-embedded domains by changing their conformation along the ion conduction pathway. Inward rectifier K(+) (Kir) channels possess a unique extramembrane cytoplasmic domain that extends this pathway. However, the relevance and contribution of this domain to ion permeation remain unclear. By qualitative x-ray crystallographic analysis, we found that the pore in the cytoplasmic domain of Kir3.2 binds cations in a valency-dependent manner and does not allow the displacement of Mg(2+) by monovalent cations or spermine. Electrophysiological analyses revealed that the cytoplasmic pore of Kir3.2 selectively binds positively charged molecules and has a higher affinity for Mg(2+) when it has a low probability of being open. The selective blocking of chemical modification of the side chain of pore-facing residues by Mg(2+) indicates that the mode of binding of Mg(2+) is likely to be similar to that observed in the crystal structure. These results indicate that the Kir3.2 crystal structure has a closed conformation with a negative electrostatic field potential at the cytoplasmic pore, the potential of which may be controlled by conformational changes in the cytoplasmic domain to regulate ion diffusion along the pore.
Interactions of cations with the cytoplasmic pores of inward rectifier K(+) channels in the closed state.,Inanobe A, Nakagawa A, Kurachi Y J Biol Chem. 2011 Dec 2;286(48):41801-11. Epub 2011 Oct 9. PMID:21982822<ref>PMID:21982822</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
==See Also==
*[[Potassium channel 3D structures|Potassium channel 3D structures]]
*[[Potassium channel 3D structures|Potassium channel 3D structures]]
== References ==
<references/>
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Latest revision as of 14:02, 13 March 2024

Crystal Structure of the Kir3.2 Cytoplasmic Domain (Na+-free crystal soaked in 10 mM Gadolinium chloride and 10 mM magnesium chloride)

3atd, resolution 3.01Å

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