Which of the following is true about the molecular structure of voltage-gated sodium channels?
A. They are single polypetide chains with 4-6 heterologous subunits (alpha helices) and a voltage sensor on the S5 segment
B. The α subunits are single polypeptide chains organized in four homologous domains, which each contain six transmembrane alpha helices (S1–S6) and an additional pore loop located between the S5 and S6 segments
C. The α subunits are comprised of 4 heterologous subunits that are connected by a pore loop located between the S5 and S6 segments.
D. The pore-forming α subunit is accompanied by 1 or 2 β-subunits which modulate channel gating and localization of the channel in the membrane.
E. The presence of a β-subunit means that the channel has an inactivation gate, which blocks the channels according to a "ball-and-chain" model. Channels without β-subunits have properties of "persistent sodium currents" that do not inactivate
F. Answers B and D are true