Figure 1.

Structure and localization of glycosylation sites of VGSC. The primary structures of the subunits of the voltage-gated ion channels are illustrated as transmembrane-folding diagrams. Cylinders represent probable α-helical segments. Bold lines in red represent the polypeptide chains of each subunit, with length approximately proportional to the number of amino acid residues in the brain sodium channel subtypes. The extracellular domains of the β1 and β2 subunits are shown as immunoglobulin-like folds. Sites of probable N-linked glycosylation; open circle with “—”, amino residues that form the ion selectivity filter and tetrodotoxin binding site.