6uz3 | pdb_00006uz3
Cardiac sodium channel
Structural highlights
Function[SCN5A_RAT] This protein mediates the voltage-dependent sodium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a sodium-selective channel through which Na(+) ions may pass in accordance with their electrochemical gradient. It is a tetrodotoxin-resistant Na(+) channel isoform. This channel is responsible for the initial upstroke of the action potential. Channel inactivation is regulated by intracellular calcium levels.[UniProtKB:Q14524][UniProtKB:Q9JJV9] Publication Abstract from PubMedVoltage-gated sodium channel Nav1.5 generates cardiac action potentials and initiates the heartbeat. Here, we report structures of NaV1.5 at 3.2-3.5 A resolution. NaV1.5 is distinguished from other sodium channels by a unique glycosyl moiety and loss of disulfide-bonding capability at the NaVbeta subunit-interaction sites. The antiarrhythmic drug flecainide specifically targets the central cavity of the pore. The voltage sensors are partially activated, and the fast-inactivation gate is partially closed. Activation of the voltage sensor of Domain III allows binding of the isoleucine-phenylalanine-methionine (IFM) motif to the inactivation-gate receptor. Asp and Ala, in the selectivity motif DEKA, line the walls of the ion-selectivity filter, whereas Glu and Lys are in positions to accept and release Na(+) ions via a charge-delocalization network. Arrhythmia mutation sites undergo large translocations during gating, providing a potential mechanism for pathogenic effects. Our results provide detailed insights into Nav1.5 structure, pharmacology, activation, inactivation, ion selectivity, and arrhythmias. Structure of the Cardiac Sodium Channel.,Jiang D, Shi H, Tonggu L, Gamal El-Din TM, Lenaeus MJ, Zhao Y, Yoshioka C, Zheng N, Catterall WA Cell. 2019 Dec 13. pii: S0092-8674(19)31326-1. doi: 10.1016/j.cell.2019.11.041. PMID:31866066[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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