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PDBsum entry 1zv0
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Signaling protein
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PDB id
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1zv0
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References listed in PDB file
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Key reference
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Title
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Determining the environment of the ligand binding pocket of the human angiotensin ii type i (hat1) receptor using the methionine proximity assay.
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Authors
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M.Clément,
S.S.Martin,
M.E.Beaulieu,
C.Chamberland,
P.Lavigne,
R.Leduc,
G.Guillemette,
E.Escher.
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Ref.
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J Biol Chem, 2005,
280,
27121-27129.
[DOI no: ]
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PubMed id
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Abstract
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The peptide hormone angiotensin II (AngII) binds to the AT0 (angiotensin type 1)
receptor within the transmembrane domains in an extended conformation, and its
C-terminal residue interacts with transmembrane domain VII at Phe-293/Asn-294.
The molecular environment of this binding pocket remains to be elucidated. The
preferential binding of benzophenone photolabels to methionine residues in the
target structure has enabled us to design an experimental approach called the
methionine proximity assay, which is based on systematic mutagenesis and
photolabeling to determine the molecular environment of this binding pocket. A
series of 44 transmembrane domain III, VI, and VII X --> Met mutants
photolabeled either with 125I-[Sar1,p'-benzoyl-L-Phe8]AngII or with
125I-[Sar1,p''-methoxy-p'-benzoyl-L-Phe8]AngII were purified and digested with
cyanogen bromide. Several mutants produced digestion patterns different from
that observed with wild type human AT1, indicating that they had a new receptor
contact with position 8 of AngII. The following residues form this binding
pocket: L112M and Y113M in transmembrane domain (TMD) III; F249M, W253M, H256M,
and T260M in TMD VI; and F293M, N294M, N295M, C296M, and L297M in TMD VII.
Homology modeling and incorporation of these contacts allowed us to develop an
evidence-based molecular model of interactions with human AT1 that is very
similar to the rhodopsin-retinal interaction.
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Figure 6.
FIG. 6. Reaction scheme of photoactivated Bpa with a Met
residue and the ensuring CNBr cleavage products. The asterisk
(*) indicates a radioactive label for autoradiographic
detection. The  -pathway produces
labeled protein fragments only, and the  pathway produces ligand
release.
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Figure 7.
FIG. 7. Molecular model of the [Sar1,Bpa^8]AngII-liganded
hAT[1] receptor. A, side view. The receptor backbone is shown in
gray, Met-mutated residues are either blue (MPA-negative) or
green (MPA-positive). The ligand is shown in yellow with a mesh
surface of the benzophenone residue. For clarity, the ligand
side chains are omitted except for the Bpa residue in position
8. B, top view of the transmembrane section; color
identification is the same as described for panel A. Only the
position of the Bpa residue is shown.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2005,
280,
27121-27129)
copyright 2005.
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