Fig. 4. SWS1 opsins. (A) Deduced amino acid sequences from six species of notothenioid fish (GenBank accession numbers AY927651-6). The Phe residue at the equivalent site to 86 in the bovine opsin sequence that is critically important for tuning into the UV is boxed, together with the counterion Glu at the equivalent site to 113 and the Lys at the equivalent site to 296 that binds the chromophore. (B) In vitro absorbance spectrum for the pigment from D. mawsoni. Recombinant SWS1 opsin was produced in transfected HEK 293T cells and the pigment regenerated with 11-cis-retinal. The difference spectrum shown with a fitted Govardovski visual pigment template, was obtained by subtracting the acid-denatured spectrum from the dark spectrum.