Crucial in the assembly, expression, and functional modulation of the heterotrimeric complex of the sodium channel. The subunit beta-2 causes an increase in the plasma membrane surface area and in its folding into microvilli. Interacts with TNR may play a crucial role in clustering and regulation of activity of sodium channels at nodes of Ranvier (By similarity). The voltage-sensitive sodium channel consists of an ion conducting pore forming alpha-subunit (SCN2A) regulated by one or more beta subunits (SCN1B, SCN2B, SCN3B and SCN4B). SCN1B and SCN3B are non-covalently associated with SCN2A. SCN2B and SCN4B are disulfide-linked to SCN2A (By similarity). Belongs to the sodium channel auxiliary subunit SCN2B (TC 8.A.17) family.