Fig. 2

Estimated absorption spectra of chimeric mutants of PxRh1 and PxRh3. The absorption spectra of WT and chimeric mutants with respect to the transmembrane helix between PxRh1_Gs (a) and PxRh3_Gs (h), Rh3(I)/Rh1(II-VII) (b), Rh3(I,II)/Rh1(III-VII) (c), Rh3(I-III)/Rh1(IV-VII) (d), Rh3(I-IV)/Rh1(V-VII) (e), Rh3(I-V)/Rh1(VI,VII) (f), Rh3(I-VI)/Rh1(VII) (g) estimated by heterologous action spectroscopy. Solid circles represent the mean relative sensitivities of cultured cells expressing each of WT or chimeric mutant at each wavelength of light irradiation (a and h; n = 9, b-g; n = 3) and black curves indicate estimated absorption spectra. Error bar represents standard errors. The estimated absorption spectra of PxRh1_Gs and PxRh3_Gs are also indicated by green and magenta broken curves, respectively. Schematic drawings of seven transmembrane structures of butterfly opsins are also shown, in which helices of PxRh1 and PxRh3 are indicated by green and magenta, respectively