The Nav β-subunit gene family consists of four members: β1 (SCN1B), β2 (SCN2B), β3 (SCN3B), and β4 (SCN4B) having type I topology, containing an extracellular amino-terminus, a single transmembrane segment, and an intracellular carboxyl-terminus.They modulate channel gating, assembly, and cell surface expression in heterologous cell systems.Navβ-subunits are cell adhesion molecules of the Ig superfamily, which interact with extracellular matrix, transmembrane signaling, and cell adhesion molecules.In the adult central nervous system and heart, sodium channels are associate with β1- β4 subunits, whereas in adult skeletal muscle they are associate only with the β1 subunitThis association appears to be a late event in sodium channel biosynthesis