This domain is the C-terminal ligand binding domain of many members of the GntR family. This domain binds to a range of effector molecules, including Lactate, Zn(II), Ni(II), Ca(II), Mg(II), citrate, sugar acids, sialic acid and N-acetylglucosamine-6-P, that regulate the transcription of genes through the action of the N-terminal DNA-binding domain Pfam:PF00392 (Matilla et. al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043). This domain is found in Swiss:P45427 and Swiss:P31460 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 [1]. This family has been named as FCD for (FadR C-terminal Domain).

1: Crystal structure of FadR, a fatty acid-responsive transcription factor with a novel acyl coenzyme A-binding fold. van Aalten DM, DiRusso CC, Knudsen J, Wierenga RK; EMBO J 2000;19:5167-5177. PMID:11013219