Fig. 5.

Sequence alignments of the human m2 mAChR (Hs-M2), rat m3 (Rn-M3), D. melanogaster A-type (Dm-mAChR-A), T. castaneum A-type (Tc-mAChR-A), C. elegans A-type (Ce-GAR-3), D. melanogaster B-type (Dm-mAChR-B), T. castaneum B-type (Tc-mAChR-B), and the two C. elegans B-type mAChRs (Ce-GAR-1 and -2). The 14 QNB binding residues of the human m2 receptor [19] are indicated by numbers above the m2 sequence and highlighted in both red and grey. The red numbers are the proposed (“modeled”) binding residues for acetylcholine [19]. The transmembrane helices are indicated by TM1-TMVII. Cystine bridges are highlighted in yellow and indicated by “S–S”. The amino acids residues that are identical in all five A-type mAChRs are highlighted in orange; those that are identical in all B-type mAChRs are highlighted in blue. Green indicates residues that are identical in both A- and B-type mAChRs