1epb
STRUCTURE OF THE EPIDIDYMAL RETINOIC ACID-BINDING PROTEIN AT 2.1 ANGSTROMS RESOLUTION
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OverviewOverview
BACKGROUND: Androgen-dependent proteins in the lumen of the epididymis are required for sperm maturation. One of these is a retinoic acid binding protein, E-RABP, which binds both all-trans and 9-cis retinoic acid. The other retinoid-binding proteins whose structures are known do not bind 9-cis retinoids. RESULTS: We describe the X-ray structure determination of E-RABP with and without bound ligand. The ligand binds deep in the beta-barrel of the protein, the beta-ionone ring innermost. The binding site, like the ligand, is amphipathic and the deepest part of the cavity is formed by a ring of aromatic amino acids. The isoprene tail of all-trans retinoic acid is bound in a folded conformation which resembles that of the 9-cis isomer. CONCLUSION: E-RABP achieves high-affinity binding of both all-trans and 9-cis isomers of retinoic acid by forcing the all-trans form to bind in a folded conformation. The RAR family of nuclear receptors for retinoic acid also binds both isomers, and their binding sites may therefore be similar.
About this StructureAbout this Structure
1EPB is a Single protein structure of sequence from Rattus norvegicus with as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Structure of the epididymal retinoic acid binding protein at 2.1 A resolution., Newcomer ME, Structure. 1993 Sep 15;1(1):7-18. PMID:8069623
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