This domain is a CTP-dependent riboflavin kinase (RFK), found in archaea, that catalyses the phosphorylation of riboflavin to form flavin mononucleotide in riboflavin biosynthesis EC:2.7.1.26. Its structure resembles a RIFT barrel, structurally similar to but topologically distinct from bacterial and eukaryotic examples. The N-terminal is a winged helix-turn-helix DNA-binding domain, and the C-terminal half is most similar in sequence to a group of cradle-loop barrels. Swiss:O28174 has this domain attached to Pfam:PF00325.

1: A CTP-Dependent Archaeal Riboflavin Kinase Forms a Bridge in the Evolution of Cradle-Loop Barrels. Ammelburg M, Hartmann MD, Djuranovic S, Alva V, Koretke KK, Martin J, Sauer G, Truffault V, Zeth K, Lupas AN, Coles M; Structure. 2007;15:1577-1590. PMID:18073108