Fig. 6

Analyses of chimeric mutants of pufferfish parapinopsin, indicating the importance of helix II in the spectral tuning of teleost parapinopsin. a–d Absorption spectra of chimeric mutants (black curves) composed of pufferfish PP1 and PP2 helices (magenta and cyan, respectively, insets). Mutants containing helices I and II of PP1 and helices III–VII of PP2 (a), and the mutant containing only helix II of PP1 in the background of PP2 (b) exhibit their absorption maximum in the UV region. The mutant containing helices I–III of PP2 and helices IV–VII of PP1 (c) exhibits absorption in the visible region, whereas the mutant containing only helix III of PP2 and helices I, II, IV–VII of PP1 (d) remains a UV-sensitive pigment. e Comparison of the amino acid sequences of helix II among teleost parapinopsins. The horizontal bar on the alignment indicates helix II. Sites 86 and 89 in the parapinopsins are highlighted. Note that mutants containing only helix I of PP1 in the background of PP2 or helices I and/or II of PP2 in the background of PP1 were not expressed