Voltage-gated sodium channels isolated from mammalian brain are composed of α, β1, and
β2 subunits. The α subunit forms the ion conducting pore of the channel, whereas the β1
and β2 subunits modulate channel function, as well as channel plasma membrane
expression levels. β1 and β2 each contain a single, extracellular Ig-like domain with
structural similarity to the neural cell adhesion molecule (CAM), myelin Po. β2 contains
strong amino acid homology to the third Ig domain and to the juxtamembrane region of …