Purity: > 95% by SDS-PAGE Format: Liquid in 20mM Tris pH 7.5, 0.1M NaCl, 5mM beta-mercaptoethanol . Retinoic acid receptors (RAR) belong to the large family of ligand responsive gene regulatory proteins that includes receptors for steroid and thyroid hormones. These proteins contain two highly conserved domains that are involved in determining their DNA and ligand-binding activities. Three isotypes of RARs, alpha, beta, and gamma, are encoded by distinct genetic loci and possess distinct transcriptional properties. Typically, RAR-alpha represses target gene transcription in the absence of hormone, whereas RAR-beta and gamma fail to repress under these conditions. Recombinant human RARalpha, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.