Figure 5. Conservation of the intracellular Na⁺ ion pathway.

Muscarinic m2 receptor shown in blue cartoon representation, along with ball-and-stick representation of residues involved in the egress of the Na⁺ ion. The carbon atoms of 17 residues that are >90% conserved among aminergic receptors are shown in green, the carbon atoms of additional 15 residues that are conserved among the muscarinic family of receptors are shown in yellow, the carbon atoms of the 4 non-conserved residues are shown in orange.