TR4/NR2C2 Proteins and Enzymes

TR4 (TAK1, NR2C2) is an orphan nuclear receptor. TR4 was originally cloned from lymphoblastoma Raji cells or mouse brain cDNA library. No ligand has been reported. Northern blot shows TR4 is transcribed as a 9kb mRNA in many tissues and as a 2.8kb mRNA in testis, mainly in spermatocytes. TR4 has two isoforms called TR4alpha1 and TR4 alpha2,which differ in 19 amino acids coded by two separate exons. Both products translated from the 9kb transcript are ubiquitously expressed. Since TR4 binds to the same elements for the RAR-RXR or TR-RXR heterodimers, TR4 may have an inhibitory effect for retinoic-acid mediated transactivation.