A Sequence of 24 Hydrophobic Amino Acids at the Amino

A sequence of 24 hydrophobic amino acids at the amino tail of the nAChR subunit ensures

A) that ligand binding occurs principally on the α-subunit (and not β, γ, or δ) .
B) M1-M4 transmembrane domains align in parallel.
C) that nAChRs can dimerize.
D) that the first transmembrane domain (M1) forms an helix as required for intercalation in the membrane.
E) that ligand-binding sites reside extracellularly.