1fbm
From Proteopedia
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ASSEMBLY DOMAIN OF CARTILAGE OLIGOMERIC MATRIX PROTEIN IN COMPLEX WITH ALL-TRANS RETINOL
Overview
The potential storage and delivery function of cartilage oligomeric matrix, protein (COMP) for cell signaling molecules was explored by binding, hydrophobic compounds to the recombinant five-stranded coiled-coil domain, of COMP. Complex formation with benzene, cyclohexane, vitamin D3 and, elaidic acid was demonstrated through increases in denaturation, temperatures of 2-10 degreesC. For all-trans retinol and all-trans, retinoic acid, an equilibrium dissociation constant KD = 0.6 microM was, evaluated by fluorescence titration. Binding of benzene and all-trans, retinol into the hydrophobic axial pore of the COMP coiled-coil domain was, proven by the X-ray crystal structures of the corresponding complexes at, 0.25 and 0.27 nm resolution, respectively. Benzene binds with its plane, perpendicular to the pore axis. The binding site is between the two, internal rings formed by Leu37 and Thr40 pointing into the pore of the, COMP coiled-coil domain. The retinol beta-ionone ring is positioned in a, hydrophobic environment near Thr40, and the 1.1 nm long isoprene tail, follows a completely hydrophobic region of the pore. Its terminal hydroxyl, group complexes with a ring of the five side chains of Gln54. A mutant in, which Gln54 is replaced by Ile binds all-trans retinol with affinity, similar to the wild-type, demonstrating that hydrophobic interactions are, predominant.
About this Structure
1FBM is a Single protein structure of sequence from Rattus norvegicus with RTL as ligand. Full crystallographic information is available from OCA.
Reference
All-trans retinol, vitamin D and other hydrophobic compounds bind in the axial pore of the five-stranded coiled-coil domain of cartilage oligomeric matrix protein., Guo Y, Bozic D, Malashkevich VN, Kammerer RA, Schulthess T, Engel J, EMBO J. 1998 Sep 15;17(18):5265-72. PMID:9736606
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