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Title
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Crystallographic studies on a family of cellular lipophilic transport proteins. Refinement of P2 myelin protein and the structure determination and refinement of cellular retinol-binding protein in complex with all-trans-retinol.
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Authors
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S.W.Cowan,
M.E.Newcomer,
T.A.Jones.
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Ref.
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J Mol Biol, 1993,
230,
1225-1246.
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PubMed id
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Abstract
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P2 myelin protein (P2) and cellular retinol binding protein (CRBP) are members
of a family of cellular lipophilic transport proteins. P2 has been refined at a
resolution of 2.7 A, and CRBP has been solved by molecular replacement and
refined to a resolution of 2.1 A. The members of this family form a compact
three-dimensional structure built up from ten antiparallel strands that fold to
form an orthogonal barrel containing the ligand. In P2, the carboxylate group of
an oleic acid ligand interacts with the side-chains of two arginine (106 and
126), and one tyrosine (128) residues. The ligand adopts a U-shaped
conformation. In CRBP, the all-trans-retinol has a planar conformation with its
alcohol group hydrogen bonding to the side-chain of glutamine 108 (equivalent to
residue 106 in P2). The local interactions of glutamine 108 explain CRBP's
preference for binding retinol rather than retinal. The side-chain of lysine 40
makes a close contact with the isoprene tail of the retinol.
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