Maximal Channel Current in NAChRs Depends on

Maximal channel current in nAChRs depends on

A) leucine and valine at 9′, 13′, and 16′ in the M2 helix.
B) hydrophobic isoleucine adjacent to lipid or other parts of the protein's secondary or tertiary structure.
C) substitution of serine at 6′ in the M2 helix with a more hydrophilic amino acid.
D) substitution of serine at 6′ in the M2 helix with a more hydrophobic amino acid.
E) hydrophilic serine at 6′ in the M2 helix.