Multiple sequence alignment was carried out using ClustalW and ESPript. Secondary-structural elements are shown above the sequence. Completely conserved residues are highlighted in red. Loop1 (Tyr515-Gln529) and Loop2 (Asn652-Ser665) are labeled and indicated by green boxes. The pink box stands for the histidine residue involved in the binding of Chl1A. The species shown are Gloeobacter violaceus PCC 7421, Thermosynechococcus elongatus BP-1, Thermosynechococcus vulcanus NIES-2134, Synechocystis sp. PCC 6803, Halomicronema hongdechloris C2206, and Acaryochloris marina MBIC11017.