Sodium channel protein type alpha subunit (Nav)

The sodium channel protein type alpha subunits, collectively known as voltage-gated sodium channels' pore-forming units ("Nav"), are large transmembrane proteins responsible for rapid influx of Na+ ions during action potentials in excitable tissues such as nerves and muscles.[2] Each functional mammalian voltage-gated sodium channel consists primarily of a single large (~2000 amino acids) α-subunit that forms a central ion-conducting pore with four homologous domains containing six membrane-spanning segments each.[2] These α-subunits may associate with one or more β-subunits that modulate their function but are not required for basic activity.[6] There are nine main human α-subunits encoded by different genes—each showing tissue-specific expression patterns—and they play critical roles in electrical signaling throughout the nervous system and heart.[2][3] Mutations can lead to diverse pathologies ranging from epilepsy and chronic pain syndromes to life-threatening arrhythmias.[3] They represent major drug targets across neurology, cardiology, anesthesiology, and toxicology fields due both to their essential physiological functions and their susceptibility to pharmacological modulation by small molecules or toxins.[2][3]

Other names

Voltage-gated sodium channel alpha subunitSodium channel α-subunitNaV α-subunitSpecific isoform names: Sodium channel protein type 1/2/3/4/5/6/7/8/9 subunit alpha (e.g., SCN5A = Sodium channel protein type 5 subunit alpha)Cardiac sodium channel (for SCN5A/Nav1.5)

Drugs typically act by: - Blocking the pore to inhibit Na+ influx ("sodium current blockade") - Stabilizing the inactive state of the voltage sensor/gate - Modulating gating kinetics to reduce excitability or conduction velocity Some toxins bind selectively to extracellular sites on specific domains/subtypes.