Respiratory nitrate reductase A (NarGHI), alpha chain (NarG) and related proteins. Under anaerobic conditions in the presence of nitrate, E. coli synthesizes the cytoplasmic membrane-bound quinol-nitrate oxidoreductase (NarGHI), which reduces nitrate to nitrite and forms part of a redox loop generating a proton-motive force. Found in prokaryotes and some archaea, NarGHI usually functions as a heterotrimer. The alpha chain contains the molybdenum cofactor-containing Mo-bisMGD catalytic subunit. This CD (MopB_CT_Nitrate-R-NarG-like) 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.",