Genomic organization of the human retinoic acid receptor β2

Abstract Recently three isoforms of the mouse retinoic acid receptor (mRARβ1, mRARβ2, mRARβ3) have been described, generated from the same gene (Zelent et al. , 1991). The isoforms differ in their 5′-untranslated (5′-UTR) and A region, but have identical B to F regions. The N-terminal variability of mRAR β1 β3 is encoded in the first two exons (El and E2), while exon E3 includes N-terminal sequences of the mRARβ2 isoform. We have determined the structure of the human RARβ2 gene, using a genomic library from K562 cells. The open reading frame is split into eight exons: E3 contains sequences for the N-terminal A region and E4 to E10 encode the common part of the receptor, including the DNA-binding domain and ligand-binding domain. Corresponding to other nuclear receptors, both ‘zinc-forgers’ of the DNA-binding domain are encoded separately in two exons and the ligand-binding domain is assembled from five exons.