FIGURE 2.

A, positions of three amino acid residues consisting of the motif. X-ray crystal structure of BR (PDB code 1C3W) is shown from a view parallel to the membrane. The central part is magnified and the helix C is shown in pink. Three motif residues, Asp-85, Thr-89, and Asp-96, are shown in sticks together with the retinal bound to Lys-216 via PSB. The corresponding residues in MrHR, Thr-74, Ser-78, and Asp-85 are indicated in the parentheses. B, comparison of the important residues, especially the motifs among the ion pumps. NpHR, HR from Natronomonas pharaonis.