Bestrophin-3 is a 668 amino acid member of the Bestrophin family of proteins. Members of the Bestrophin family are transmembrane proteins that contain a high percentage of aromatic residues, a conserved RFP (arg-phe-pro) motif and they function as anion channels. Expressed predominantly in skeletal muscle but also found in spinal cord, brain, testis, thymus, retina and bone marrow, Bestrophin-3 forms calcium-sensitive chloride channels. In addition, Bestrophin-3 contains an AI (auto-inhibitory) domain that is capable of regulating the anion channel activity. Due to alternative splicing events, three isoforms exist for Bestrophin-3.