Table 1. Cys-loop aromatic box residues^a.

Receptor	Loop A	Loop B	Loop C		Loop D
nAChR	Y93	W149	Y190	Y198	W55
5-HT3	E129b	W183	F226	Y234	W90
MOD-1	C120	Y180	Y221	W226	F83
GABAC	F138	Y198	Y241	Y247	Y102
GABAA	Y97	Y157	F200	Y205	F65

^aResidues previously identified as contributing to cation-π bonds are typed in bold.

^bSee Sullivan et al. (2006).