Figure 2.

Cartoon representation for the crystal structure of PAS-GAF-PHY domains of DrBphP in the (a) Pr-dark state (PDB: 4O0P(5)) that absorbs red light (700 nm) to trigger the secondary structure rearrangement from β-sheets to α-helix (orange) and a PHY domain opening to form the (b) Pfr-illuminated state (PDB: 4O01(5)) that absorbs far-red light (750 nm) to revert back to the Pr state; (c,d) experimental UV/vis absorption spectrum reported by Takala et al., which exhibits the Q-band and Soret band for Pr and Pfr states, respectively.⁵