根拠: homology, The structure is homologous to structure 2DRE, which is a tetramer. Due to unknown reasons structure 5HPZ, which is the same structure as our structure only differing in chlorphyll ...根拠: homology, The structure is homologous to structure 2DRE, which is a tetramer. Due to unknown reasons structure 5HPZ, which is the same structure as our structure only differing in chlorphyll ligand, is annotated as dimer in the database. The tetramer with the chlorophyll ligands in the central cavity can be easily seen in the unit cell by symmetry operation from ASU.