Amino acid replacements (orange circles) associated with melanism vary slightly in location in different species but are located in the same part of the MC1R protein. The upper part of the figure shows the general topology of the MC1R protein. The region in which replacements are located is enlarged in the lower part of the figure.
[Data from E. Eizirik et al., “Molecular Genetics and Evolution in the Cat Family,” Curr. Biol. 13, 2003, 448-