Structural highlights
Function
[KCAB2_RAT] Accessory potassium channel protein which modulates the activity of the pore-forming alpha subunit. [KCNA2_RAT] Mediates the voltage-dependent potassium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a potassium-selective channel through which potassium ions may pass in accordance with their electrochemical gradient.[1]
Publication Abstract from PubMed
C-type inactivation underlies important roles played by voltage-gated K+ (Kv) channels. Functional studies have provided strong evidence that a common underlying cause of this type of inactivation is an alteration near the extracellular end of the channel's ion-selectivity filter. Unlike N-type inactivation, which is known to reflect occlusion of the channel's intracellular end, the structural mechanism of C-type inactivation remains controversial and may have many detailed variations. Here we report that in voltage-gated Shaker K+ channels lacking N-type inactivation, a mutation enhancing inactivation disrupts the outermost K+ site in the selectivity filter. Furthermore, in a crystal structure of the Kv1.2-2.1 chimeric channel bearing the same mutation, the outermost K+ site, which is formed by eight carbonyl-oxygen atoms, appears to be slightly too small to readily accommodate a K+ ion and in fact exhibits little ion density; this structural finding is consistent with the functional hallmark of C-type inactivation.
Crystal structure of an inactivated mutant mammalian voltage-gated K+ channel.,Pau V, Zhou Y, Ramu Y, Xu Y, Lu Z Nat Struct Mol Biol. 2017 Aug 28. doi: 10.1038/nsmb.3457. PMID:28846092[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Lev S, Moreno H, Martinez R, Canoll P, Peles E, Musacchio JM, Plowman GD, Rudy B, Schlessinger J. Protein tyrosine kinase PYK2 involved in Ca(2+)-induced regulation of ion channel and MAP kinase functions. Nature. 1995 Aug 31;376(6543):737-45. PMID:7544443 doi:http://dx.doi.org/10.1038/376737a0
- ↑ Pau V, Zhou Y, Ramu Y, Xu Y, Lu Z. Crystal structure of an inactivated mutant mammalian voltage-gated K+ channel. Nat Struct Mol Biol. 2017 Aug 28. doi: 10.1038/nsmb.3457. PMID:28846092 doi:http://dx.doi.org/10.1038/nsmb.3457
