GENOMIC ORGANIZATION OF THE HUMAN RETINOIC ACID RECEPTOR BETA-2

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 mRARβ1 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. © 1992.