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PDBsum entry 3e3r
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Calcium binding protein
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PDB id
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3e3r
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References listed in PDB file
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Key reference
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Title
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Crystal-Structure and biochemical characterization of recombinant human calcyphosine delineates a novel ef-Hand-Containing protein family.
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Authors
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H.Dong,
X.Li,
Z.Lou,
X.Xu,
D.Su,
X.Zhou,
W.Zhou,
M.Bartlam,
Z.Rao.
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Ref.
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J Mol Biol, 2008,
383,
455-464.
[DOI no: ]
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PubMed id
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Abstract
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Calcyphosine is an EF-hand protein involved in both Ca(2+)-phosphatidylinositol
and cyclic AMP signal cascades, as well as in other cellular functions. The
crystal structure of Ca(2+)-loaded calcyphosine was determined up to 2.65 A
resolution and reveals a protein containing two pairs of Ca(2+)-binding EF-hand
motifs. Calcyphosine shares a highly similar overall topology with calmodulin.
However, there are striking differences between EF-hand 4, both N-terminal and
C-terminal regions, and interdomain linkers. The C-terminal domain of
calcyphosine possesses a large hydrophobic pocket in the presence of calcium
ions that might be implicated in ligand binding, while its N-terminal
hydrophobic pocket is almost shielded by an additional terminal helix.
Calcyphosine is largely monomeric, regardless of the presence of Ca(2+).
Differences in structure, oligomeric state in the presence and in the absence of
Ca(2+), a highly conserved sequence with low similarity to other proteins, and
phylogeny define a new EF-hand-containing family of calcyphosine proteins that
extends from arthropods to humans.
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Figure 3.
Fig. 3. Comparison of calcyphosine with CaM. (a) Evolutionary
relationship of calcyphosine with some of its nearest homologs.
The sequences of some typical Ca^2 +-binding proteins with four
EF-hand motifs were aligned using ClustalW, and the output tree
file was displayed as a dendrogram using the program TreeView
1.6.6. The proteins are human proteins, unless stated in the
dendrogram. (b) Superposition of calcyphosine and CaM (PDB code
1CLL) based on EF-hands 3 and 4. The color scheme is the same as
for Fig. 1a, with CaM shown in magenta. All figures were
prepared using PyMOL (http://www.pymol.org). (c) Sequence
alignment of calcyphosine with CaM. N-terminal additional
α-helix αA and C-terminal inserted α-helix αJ are shown in
blue boxes. Residues that correspond to the target recognition
in the C-domain of CaM are highlighted with cyan spheres.
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Figure 4.
Fig. 4. Superposition of calcyphosine with CaM–target
complexes. (a) Superposition of the N-terminal and C-terminal
domains of calcyphosine with the CaM–CaMKK complex. CaM is
shown in magenta; the CaMKK α-helical fragment is shown in red;
the calcyphosine N-terminal domain is shown in green; the
C-terminal domain is shown in cyan. (b) Electrostatic surface
representation of the CaM–EF complex and calcyphosine. The
region of EF in contact with CaM is shown as a helical worm in
the binding sites of CaM.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2008,
383,
455-464)
copyright 2008.
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