voltage-gated sodium channel subunit alpha PIRSF:PIRSF002448 PR:000001975 A voltage-gated sodium channel protein that has a core architecture consisting of four similar domains (I-VI), each containing six transmembrane helices (S1-S6), with a pore loop between S5 and S6. The S4 segments contain positively charged amino acids at every third position and serve as voltage sensors. These large proteins (about 2000 amino acids) contain a unique Sodium ion transport-associated domain (Pfam:PF06512) located between two pairs of Ion transport protein domains (Pfam:PF00520). An IQ calmodulin-binding motif (Pfam:PF00612) may be found about 100 amino acids from the carboxyl end. protein Category=family. voltage-gated sodium channel protein