1u4e
From Proteopedia
Crystal Structure of Cytoplasmic Domains of GIRK1 channel
Structural highlights
Function[IRK3_MOUSE] This potassium channel is controlled by G proteins. 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. This receptor plays a crucial role in regulating the heartbeat. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedN- and C-terminal cytoplasmic domains of inwardly rectifying K (Kir) channels control the ion-permeation pathway through diverse interactions with small molecules and protein ligands in the cytoplasm. Two new crystal structures of the cytoplasmic domains of Kir2.1 (Kir2.1(L)) and the G protein-sensitive Kir3.1 (Kir3.1(S)) channels in the absence of PIP(2) show the cytoplasmic ion-permeation pathways occluded by four cytoplasmic loops that form a girdle around the central pore (G-loop). Significant flexibility of the pore-facing G-loop of Kir2.1(L) and Kir3.1(S) suggests a possible role as a diffusion barrier between cytoplasmic and transmembrane pores. Consistent with this, mutations of the G-loop disrupted gating or inward rectification. Structural comparison shows a di-aspartate cluster on the distal end of the cytoplasmic pore of Kir2.1(L) that is important for modulating inward rectification. Taken together, these results suggest the cytoplasmic domains of Kir channels undergo structural changes to modulate gating and inward rectification. Cytoplasmic domain structures of Kir2.1 and Kir3.1 show sites for modulating gating and rectification.,Pegan S, Arrabit C, Zhou W, Kwiatkowski W, Collins A, Slesinger PA, Choe S Nat Neurosci. 2005 Mar;8(3):279-87. Epub 2005 Feb 20. PMID:15723059[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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