Versatile copurification procedure for rapid isolation of homogeneous RAR-RXR heterodimers

RAR-RXR heterodimeric complexes (RAR alpha Delta AB-RXR alpha Delta AB) bou nd to cognate DR5 DNA response elements were purified to apparent structura l and functional homogeneity using a novel versatile immobilized metal affi nity chromatography (IMAC) copurification procedure. Dynamic light scatteri ng studies indicated that the complexes were more than 85% monodisperse. By electron microscopy the negatively stained RAR-RXR-DNA complexes appeared homogeneous and corresponded to a dimeric arrangement of the molecules. Usi ng heterodimers purified according to this procedure we demonstrate ligand binding of RXR in the context of the RAR-RXR heterodimer-DNA complex. The p resent copurification procedure is rapid and has yielded high quality heter odimer-DNA complexes suitable for both structural and biochemical studies. (C) 1999 Academic Press.