Fig. 3.

Comparison of residues lining the extracellular vestibule of the M₂ and M₅ mAChR. M₂•NMS is shown in dark blue and M₅•tiotropium in green. Conserved residues are labeled black, and nonconserved residues have colored labels based on receptor subtype. Residues are numbered based on the M₅ mAChR, with residues in ECL2 numbered relative to the conserved cysteine in ECL2, which is shown as a yellow sphere. Sidechains for D469^6.62 and K470^ECL3 are truncated to the β-carbon in the deposited model due to a lack of sidechain density and are modeled here as the most probable rotamer.