Fig. 4

Evaluation of the involvement of helix3 of PxRh3 in the red-shift. The absorption spectra of chimeric mutants with respect to the transmembrane helix between PxRh1_Gs and PxRh3_Gs, Rh3(II)/Rh1(I,III-VII) (a), Rh3(I,III)/Rh1(II,IV-VII) (b), Rh3(II-IV)/Rh1(I,V-VII) (c), Rh3(I,III,IV)/Rh1(II,V-VII) (d), Rh1(I)/Rh3(II-VII) (e), Rh1(III)/Rh3(I,II,IV-VII) (f), Rh1(I,III)/Rh3(II,IV-VII) (g) were estimated by heterologous action spectroscopy. Solid circles represent the mean relative sensitivities of cultured cells expressing each chimeric mutant at each wavelength of light irradiation (n = 3) and black curves indicate estimated absorption spectra. The error bar shows standard error. The 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