Sodium channel beta4, a new disulfide-linked auxiliary subunit with similarity to beta2.

The principal alpha subunit of voltage-gated sodium channels is associated with auxiliary beta subunits that modify channel function and mediate protein-protein interactions. We have identified a new beta subunit termed beta4. Like the beta1-beta3 subunits, beta4 contains a cleaved signal sequence, an extracellular Ig-like fold, a transmembrane segment, and a short intracellular C-terminal tail.