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PDBsum entry 2ct9
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Metal binding protein
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PDB id
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2ct9
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References listed in PDB file
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Key reference
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Title
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Structural characterization of calcineurin b homologous protein 1.
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Authors
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Y.Naoe,
K.Arita,
H.Hashimoto,
H.Kanazawa,
M.Sato,
T.Shimizu.
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Ref.
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J Biol Chem, 2005,
280,
32372-32378.
[DOI no: ]
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PubMed id
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Abstract
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Calcineurin B homologous protein 1 (CHP1), also known as p22, is a
calcium-binding EF-hand protein that plays a role in membrane trafficking. It
binds to multiple effector proteins, including Na(+)/H(+) exchangers, a
serine/threonine kinase, and calcineurin, potentially modulating their function.
The crystal structure of calcium-bound CHP1 from rat has been determined at 2.2
Angstroms of resolution. The molecule has a compact alpha-helical structure
containing four EF-hands. The overall folding topology of the protein is similar
to that of the regulatory B subunit of calcineurin and to that of calcium- and
integrin-binding protein. The calcium ion is coordinated in typical fashion in
the third and fourth EF-hands, but the first and second EF-hands contain no
calcium ion. The first EF-hand is maintained by internal interactions, and the
second EF-hand is stabilized by hydrophobic interactions. CHP1 contains a
hydrophobic pocket on the opposite side of the protein to the EF-hands that has
been implicated in ligand binding.
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Figure 2.
FIGURE 2. Overall structure of CHP1. a, ribbon
representation of secondary structure elements.  -Helices
are colored blue, and calcium ions are depicted by yellow balls.
The -helix derived from the
vector is colored green. b, ribbon representation of the
structure of CHP1 superimposed on that of CNB. CHP1 and CNB are
represented as blue and red ribbons, respectively. The figure
was generated by superimposing the -helices of the
C-lobes. These are shown in pale blue and red. N- and C-terminal
helices ( A and J) are
omitted for clarity. The angle of rotation between the
N-terminal domains of CHP1 and CNB is  20°.
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Figure 3.
FIGURE 3. Representation of the four EF-hand motifs (EF-1,
EF-2, EF-3, EF-4). a, calcium-bound EF-hand motifs (EF-3 and
EF-4). Calcium ions and water molecules are represented as
yellow and red balls, respectively. An omit map, contoured at
the 7  level around each
calcium ion, is superimposed. Amino acid residues involved in
the calcium coordination are shown. b, calcium-unbound EF-hand
motifs (EF-1 and EF-2). Non-covalent interactions within
EF-hands are represented as dotted lines. In EF-2, residues
forming the hydrophobic core are also shown.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2005,
280,
32372-32378)
copyright 2005.
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