Figure 2

Localization of M ₁ receptors after treatment with various ligands as visualized by confocal microscopy. Cells were treated with various compounds (1 mM carbachol, 1 μM oxotremorine-M, 10 μM pilocarpine, 1 μM xanomeline, 10 μM NDMC, 10 μM AC-42 or 10 μM AC-260584) for 2 hrs at 37°C in the absence or presence of 100 nM atropine. The agonist concentrations used were chosen to ensure maximum activation of endocytic pathway. These concentrations were higher than those used in binding assays. However the possibility of residual ligand confounding the results was not a concern since the site of interaction with the monoclonal antibody (N-terminal tail of the receptor) is distinct from the agonist binding sites. Images are from a representative experiment repeated 3 times with similar results.