RAR-beta 4, a retinoic acid receptor isoform is generated from RAR-beta 2 by alternative splicing and usage of a CUG initiator codon.

An isoform of retinoic acid receptor beta, RAR-beta 4, has been identified. RAR-beta 4 is expressed under the control of the same retinoic acid-responsive promoter as RAR-beta 2. RAR-beta 4, which is generated by alternative splicing from the same primary transcripts as RAR-beta 2, is initiated by a non-AUG codon, CUG. The amino acid sequence of RAR-beta 4 in regions B-F is identical to that of the other RAR-beta isoforms beta 1, beta 2, and beta 3. However, the RAR-beta 4 A region is much shorter (4 amino acids long) than those of these isoforms. RAR-beta 4 exhibits a tissue-specific pattern of expression and distinct transcriptional activation properties when compared with the other RAR-beta isoforms. IMAGES: