Difference electron density (blue positive density, mustard negative density, arbitrary units) is represented as a function of sequence according to the procedure described by Wickstrand et al. 38 Similar difference electron density features are observed for bR and NpSRII during continuous illumination, and within the time-resolved data following a 5 ms laser-flash. Transmembrane helices of bR are indicated in transparent purple and those of SRII in transparent pink. Helix boundaries for bR are helix A, residues 6 –32; B, 37 –58; C, 80 –100; D, 105 –127; E, 131 –160; F, 165 –191; G, 201 –224. Helix boundaries for SRII are helix A, residues 3 –26; B, 33 –56; C, 70 –92; D, 94 –118; E, 122 –150; F, 153 –181; G, 189 –219.
