May function as storage protein that sequesters riboflavin and related compounds, thereby protecting the cell against undesirable reactions mediated by the free flavins. Binds and sequesters riboflavin, lumiflavin and lumichrome. Can also bind FAD and FMN (in vitro), but has low affinity for FAD and even lower affinity for FMN. Protects bound flavins against light damage; Trp-36 rapidly quenches the flavin excited state. Promotes the conversion of bound riboflavin to lumichrome. Homododecamer; four homotrimers assemble to form a dodecameric hollow sphere. Except for FAD, flavin dimers are bound between subunits with a stoichiometry of 6 flavin dimers per dodecamer. In contrast, FAD molecules are bound as monomers, where each FAD molecule forms intramolecular stacking interactions between the adenine group and the isoalloxazine group. Up-regulated upon transition to the exponential growth phase (at protein level). Not up-regulated at the RNA level. Belongs to the dodecin family. Dodecin family members from different organisms have non-identical ligand binding specificity.