Human Retbindin is a 229 amino acid secreted protein that belongs to the folate receptor family. The gene that encodes retbindin exists as two alternatively spliced isoforms. Retbindin is first expressed in retina. It may play a role in binding retinoids and other carotenoids as it shares homology with;riboflavin binding proteins. RTBDN gene was first identified in a study of human eye tissues.