Fig. 3: Opsin structural prediction with retinal binding sites, sites with higher dN/dS (positively selection) and putative tuning sites, the subset that interacts with both.
From: Light environment drives evolution of color vision genes in butterflies and moths
A UV-opsin PHOBIUS transmembrane prediction. Opsins sites with higher dN/dS rates and amino acids close to (<=4 Å) retinal, which form the retinal binding region (RBR) have been marked. B UV-opsin model made using squid rhodopsin as the template. Retinal is marked, secondary structure prediction of alpha helices are shown in different colors and the expanded view shows the positively selected sites that can interact (<=2 Å) with the retinal binding sites. Protein models used to get these metrics can be found at ref. 38. Sites under positive selection are highlighted in red, sites in the retinal binding region in yellow and positively selected sites that are capable of interacting with the retinal binding sites in pink, identifying likely candidates for opsin tuning (A). Other positively selected are located within the transmembrane region and could be indirectly involved in opsin tuning (B).
