The MopB_FmdC-FwdD CD includes the C-terminus of subunit C of molybdenum formylmethanofuran dehydrogenase (FmdC) and subunit D of tungsten formylmethanofuran dehydrogenase (FwdD), and other related proteins. Formylmethanofuran dehydrogenase catalyzes the first step in methane formation from CO2 in methanogenic archaea and some eubacteria. Members of this CD belong to the molybdopterin_binding superfamily of proteins. This CD is of the conserved molybdopterin_binding C-terminal (MopB_CT) region present in many, but not all, MopB homologs.
Jiyao W et al.(2023). "The conserved domain database in 2023.",