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PDBsum entry 1dbb
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Immunoglobulin
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PDB id
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1dbb
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Three-Dimensional structure of an anti-Steroid FAB' And progesterone-Fab' Complex.
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Authors
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J.H.Arevalo,
E.A.Stura,
M.J.Taussig,
I.A.Wilson.
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Ref.
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J Mol Biol, 1993,
231,
103-118.
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PubMed id
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Abstract
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The monoclonal anti-progesterone antibody DB3 binds progesterone with nanomolar
affinity (Ka approximately 10(9) M-1), suggesting high specificity. However, DB3
also cross-reacts with similar affinity with a subgroup of structurally
distinct, progesterone-like steroids. Crystals of the unliganded Fab' and
various steroid-Fab' complexes are isomorphous and belong to the hexagonal space
group, P6(4)22, with unit cell dimensions of a = b = 135 A, c = 124 A.
Structures of free and progesterone-bound Fab' have been determined by X-ray
crystallography at 2.7 A resolution using molecular replacement techniques.
Progesterone is bound in a hydrophobic pocket formed mainly by the interaction
of three complementarity determining regions L1, H2 and H3. The orientation of
the ligand in the binding site was aided by both crystallographic and
biochemical analyses of substituted steroids. The indole side-chain of TrpH100
of the DB3 has two different conformations, inter-converting "open" and "closed"
forms of the antibody combining site. The TrpH100 indole thus appears to be
acting as an antibody-derived surrogate ligand for its own hydrophobic binding
pocket. These structures provide the first atomic view of how a steroid
interacts with a protein and offer a structural explanation for the restriction
of the anti-progesterone response to the VGAM3.8 family of VH genes.
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Secondary reference #1
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Title
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Analysis of an anti-Progesterone antibody: variable crystal morphology of the FAB' And steroid-Fab' Complexes.
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Authors
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E.A.Stura,
J.H.Arevalo,
A.Feinstein,
R.B.Heap,
M.J.Taussig,
I.A.Wilson.
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Ref.
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Immunology, 1987,
62,
511-521.
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PubMed id
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