Biological redox reactions require electron donors and acceptor. Vitamin B2 is the source for the flavin in flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) which are common redox reagents. This gene encodes a member of the riboflavin (vitamin B2) transporter family. Haploinsufficiency of this protein can cause maternal riboflavin deficiency. Multiple alternatively spliced variants, encoding the same protein, have been identified.