8teo
Shaker in low K+ (4mM K+)
Structural highlights
FunctionKCNAS_DROME Voltage-dependent potassium channel involved in regulation of sleep need or efficiency. 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 PubMedEukaryotic voltage-gated K(+) channels have been extensively studied, but the structural bases for some of their most salient functional features remain to be established. C-type inactivation, for example, is an auto-inhibitory mechanism that confers temporal resolution to their signal-firing activity. In a recent breakthrough, studies of a mutant of Shaker that is prone to inactivate indicated that this process entails a dilation of the selectivity filter, the narrowest part of the ion conduction pathway. Here, we report an atomic-resolution cryo-electron microscopy structure that demonstrates that the wild-type channel can also adopt this dilated state. All-atom simulations corroborate this conformation is congruent with the electrophysiological characteristics of the C-type inactivated state, namely, residual K(+) conductance and altered ion specificity, and help rationalize why inactivation is accelerated or impeded by certain mutations. In summary, this study establishes the molecular basis for an important self-regulatory mechanism in eukaryotic K(+) channels, laying a solid foundation for further studies. Eukaryotic Kv channel Shaker inactivates through selectivity filter dilation rather than collapse.,Stix R, Tan XF, Bae C, Fernandez-Marino AI, Swartz KJ, Faraldo-Gomez JD Sci Adv. 2023 Dec 8;9(49):eadj5539. doi: 10.1126/sciadv.adj5539. Epub 2023 Dec 8. PMID:38064553[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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