This domain is found in glutamate synthase, tungsten formylmethanofuran dehydrogenase subunit c (FwdC) and molybdenum formylmethanofuran dehydrogenase subunit c (FmdC). A repeated G-XX-G-XXX-G motif is seen in the alignment.

1: The formylmethanofuran dehydrogenase isoenzymes in Methanobacterium wolfei and Methanobacterium thermoautotrophicum: induction of the molybdenum isoenzyme by molybdate and constitutive synthesis of the tungsten isoenzyme. Hochheimer A, Hedderich R, Thauer RK; Arch Microbiol 1998;170:389-393. PMID:9818358