Fig. 6.

The number and distribution of mutations within the TM regions. Mutation counts (x-axis) associated with conserved topological sites at the seven-transmembrane (7-TM) and ECL2 regions (a–h). Positions of natural variants (y-axis) were assigned according to the Ballesteros-Weinstein (BW) numbering system derived from their respective positions on the structure-based MSA (see the “Methods” section). The darkest regions on the y-axis bars correspond to missense substitutions. Empty circles in the snake plot at the bottom-right indicate the topological positions analyzed