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PDBsum entry 3ehs
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Membrane protein
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PDB id
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3ehs
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References listed in PDB file
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Key reference
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Title
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Molecular recognition of corticotropin-Releasing factor by its g-Protein-Coupled receptor crfr1.
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Authors
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A.A.Pioszak,
N.R.Parker,
K.Suino-Powell,
H.E.Xu.
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Ref.
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J Biol Chem, 2008,
283,
32900-32912.
[DOI no: ]
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PubMed id
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Abstract
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The bimolecular interaction between corticotropin-releasing factor (CRF), a
neuropeptide, and its type 1 receptor (CRFR1), a class B G-protein-coupled
receptor (GPCR), is crucial for activation of the hypothalamic-pituitary-adrenal
axis in response to stress, and has been a target of intense drug design for the
treatment of anxiety, depression, and related disorders. As a class B GPCR,
CRFR1 contains an N-terminal extracellular domain (ECD) that provides the
primary ligand binding determinants. Here we present three crystal structures of
the human CRFR1 ECD, one in a ligand-free form and two in distinct CRF-bound
states. The CRFR1 ECD adopts the alpha-beta-betaalpha fold observed for other
class B GPCR ECDs, but the N-terminal alpha-helix is significantly shorter and
does not contact CRF. CRF adopts a continuous alpha-helix that docks in a
hydrophobic surface of the ECD that is distinct from the peptide-binding site of
other class B GPCRs, thereby providing a basis for the specificity of ligand
recognition between CRFR1 and other class B GPCRs. The binding of CRF is
accompanied by clamp-like conformational changes of two loops of the receptor
that anchor the CRF C terminus, including the C-terminal amide group. These
structural studies provide a molecular framework for understanding peptide
binding and specificity by the CRF receptors as well as a template for designing
potent and selective CRFR1 antagonists for therapeutic applications.
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Figure 4.
Structure of the CRF-(27-41)-NH[2]-bound CRFR1 ECD at 3.4
Å resolution. A, ribbon diagram of the crystal form III
complex with the CRFR1 ECD colored slate blue and CRF yellow.
MBP is not shown for clarity. B, electron density maps for CRF.
The 2F[o] - F[c] omit map (blue) is contoured at 1 σ and the
F[o] - F[c] omit map (green) is contoured at 3 σ. The maps were
prepared as described under “Experimental Procedures.” C,
detail of the interface depicted as in Fig. 3D. D, alignment of
the crystal form II and form III structures. C-α backbone
traces are shown with the CRF-(22-41)-NH[2]-bound ECD colored
slate blue and CRF-(22-41)-NH[2] yellow. The
CRF-(27-41)-NH[2]-bound ECD is colored blue and
CRF-(27-41)-NH[2] sand.
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Figure 7.
Comparison of the hCRFR1 ECD·CRF complex and the NMR
solution structure of the mCRFR2β ECD·astressin complex.
A-C, three views of a structural alignment of the crystal form
II complex of CRF-(22-41)-NH[2] bound to the hCRFR1 ECD with the
NMR solution structure of the mCRFR2β ECD bound to astressin
(PDB code 2JND). C-α backbone traces are shown with the CRFR1
ECD·CRF complex colored slate blue and yellow,
respectively, and the CRFR2β ECD·astressin complex
colored cyan and red, respectively. D, molecular surface of the
CRFR1 ECD from crystal form II colored according to sequence
conservation between CRFR1 and CRFR2. The surface is colored
light blue for residues that are identical, blue for residues
that have conservative substitutions, and magenta for residues
that differ between the two receptors. CRF-(22-41)-NH[2] is
shown as a yellow coil. E, amino acid sequence alignment of the
human CRFR1 ECD with the human and mouse CRFR2β ECDs. Secondary
structure elements are shown at the top and the disulfide bond
connectivity at the bottom. The color scheme is the same as in
Fig. 3F.
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The above figures are
reprinted
from an Open Access publication published by the ASBMB:
J Biol Chem
(2008,
283,
32900-32912)
copyright 2008.
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