Fig. 6: Light-induced rearrangements in helices F and G on the cytoplasmic sides of of bR and NpSRII.
a Paired positive and negative difference electron density features observed for bR during continuous illumination indicate a light-induced movement of Trp182 and Ala215. b Paired positive and negative difference electron density features observed for NpSRII during continuous illumination indicate the light-induced movement of Trp171, but there is no corresponding motion associated with Thr204. c Paired positive and negative difference electron density features observed for NpSRII for Δt = 60 to 90 ms indicate similar changes in electron density as observed in panel (b). Both Fo(light) − Fo(dark) difference Fourier electron density maps are contoured at ±3.0 σ, blue, positive difference electron density; yellow, negative difference electron density. d Light-induced conformational changes in bR resulting from structural refinement against dark (white) and continuous illumination (purple) data. e Light-induced conformational changes in NpSRII resulting from structural refinement against dark (white) and continuous illumination (orange) data. f Light-induced conformational changes in NpSRII resulting from structural refinement against dark (white) and data recorded for Δt = 60–90 ms (orange). These representations indicate that movements in helix G following retinal isomerization are much reduced in NpSRII relative to bR.
