Structural highlights
Function[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 PubMedVoltage-activated potassium (Kv) channels open to conduct K(+) ions in response to membrane depolarization, and subsequently enter non-conducting states through distinct mechanisms of inactivation. X-ray structures of detergent-solubilized Kv channels appear to have captured an open state even though a non-conducting C-type inactivated state would predominate in membranes in the absence of a transmembrane voltage. However, structures for a voltage-activated ion channel in a lipid bilayer environment have not yet been reported. Here we report the structure of the Kv1.2-2.1 paddle chimera channel reconstituted into lipid nanodiscs using single-particle cryo-electron microscopy. At a resolution of ~3 A for the cytosolic domain and ~4 A for the transmembrane domain, the structure determined in nanodiscs is similar to the previously determined X-ray structure. Our findings show that large differences in structure between detergent and lipid bilayer environments are unlikely, and enable us to propose possible structural mechanisms for C-type inactivation. Single-particle cryo-EM structure of a voltage-activated potassium channel in lipid nanodiscs.,Matthies D, Bae C, Toombes GE, Fox T, Bartesaghi A, Subramaniam S, Swartz KJ Elife. 2018 Aug 15;7. pii: 37558. doi: 10.7554/eLife.37558. PMID:30109985[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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