1.A.1.14.5 Voltage-gated Na+ channel, NavCh or NavAb. The 3d-structure is known (3ROW; Payandeh et al., 2011; 4MW3A-D; 4+ selectivity through partial dehydration of Na+ via its direct interaction with conserved glutamate side chains). The pore is preferentially occupied by two ions, which can switch between different configurations by crossing low free-energy barriers (Furini and Domene, 2012). Jiang et al. 2018 presented high-resolution structures of NavAb with the analogous gating-charge mutations that have similar functional effects as in the human channels that cause hypokalaemic and normokalaemic periodic paralysis. Wisedchaisri et al. 2019 presented a cryo-EM structure of the resting state and a complete
voltage-dependent gating mechanism via the voltage sensor (VS). The S4 segment of the VS is drawn
intracellularly, with three gating charges passing through the
transmembrane electric field. This movement forms an elbow connecting S4
to the S4-S5 linker, tightens the collar around the S6 activation gate,
and prevents its opening. This structure supports the classical "sliding
helix" mechanism of voltage sensing and provides a complete gating
mechanism for voltage sensor function, pore opening, and activation-gate
closure based on high-resolution structures of a single sodium channel
protein (Wisedchaisri et al. 2019).
(see also TC#s 1.A.1.10.4 and 1.A.1.11.32).
The transport reaction catalyzed by NavCh is:
Na+ (in) ⇌ Na+ (out)
|
Accession Number: | A8EVM5 |
Protein Name: | Ion transport protein |
Length: | 267 |
Molecular Weight: | 31071.00 |
Species: | Arcobacter butzleri (strain RM4018) [367737] |
Number of TMSs: | 5 |
Substrate |
sodium(1+) |
---|
1: MYLRITNIVE SSFFTKFIIY LIVLNGITMG LETSKTFMQS FGVYTTLFNQ IVITIFTIEI
61: ILRIYVHRIS FFKDPWSLFD FFVVAISLVP TSSGFEILRV LRVLRLFRLV TAVPQMRKIV
121: SALISVIPGM LSVIALMTLF FYIFAIMATQ LFGERFPEWF GTLGESFYTL FQVMTLESWS
181: MGIVRPLMEV YPYAWVFFIP FIFVVTFVMI NLVVAIIVDA MAILNQKEEQ HIIDEVQSHE
241: DNINNEIIKL REEIVELKEL IKTSLKN