This model represents the X subunit of the three-subunit enzyme, (bacterio)chlorophyllide reductase. This enzyme is responsible for the reduction of the chlorin B-ring and is closely related to the protochlorophyllide reductase complex which reduces the D-ring. Both of these complexes in turn are homologous to nitrogenase. This subunit is homologous to the nitrogenase component II, or "iron" protein. [Energy metabolism, Photosynthesis]
Jiyao W et al.(2023). "The conserved domain database in 2023.",