Fig. 1.

a. Two orthogonal views of the PYMOL ⁴¹-generated cartoon representation of the RetS_peri structure. All secondary structure elements are labeled. b. Alignment of the secondary structure elements identified from the crystal structure with the primary structure RetS_peri. This figure was generated with ESPript ⁴². c. The asymmetric unit of the crystal consists of molecules A and B. The contacts between A and B closely resemble the packing contacts between A and the symmetry-related B’ molecule, suggesting that the dimer in the asymmetric unit arose from crystal packing contacts.