BEST3 belongs to the bestrophin family of anion channels,which includes BEST1 (MIM 607854), the gene mutant in vitelliformmacular dystrophy (VMD; MIM 153700), and 2 other BEST1-like genes,BEST2 (MIM 607335) and BEST4 (MIM 607336). Bestrophins aretransmembrane (TM) proteins that share a homology region containinga high content of aromatic residues, including an invariantarg-phe-pro (RFP) motif. The bestrophin genes share a conservedgene structure, with almost identical sizes of the 8 RFP-TMdomain-encoding exons and highly conserved exon-intron boundaries.Each of the 4 bestrophin genes has a unique 3-prime end of variablelength (Stohr et al., 2002 [PubMed 12032738]; Tsunenari et al.,2003 [PubMed 12907679]).