This domain is the C-terminal ligand binding domain of many members of the GntR family. This domain probably binds to a range of effector molecules that regulate the transcription of genes through the action of the N-terminal DNA-binding domain pfam00392. This domain is found in Escherichia coli NanR and DgoR that are regulators of sugar biosynthesis operons. It is also in the known structure of FadR where it binds to acyl-coA, the domain is alpha helical. This family has been named as FCD for (FadR C-terminal Domain).