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PDBsum entry 1jba
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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 guanylyl cyclase activating protein-2, A calcium-Sensitive modulator of photoreceptor guanylyl cyclases.
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Authors
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J.B.Ames,
A.M.Dizhoor,
M.Ikura,
K.Palczewski,
L.Stryer.
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Ref.
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J Biol Chem, 1999,
274,
19329-19337.
[DOI no: ]
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PubMed id
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Abstract
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Guanylyl cyclase activating protein-2 (GCAP-2) is a Ca2+-sensitive regulator of
phototransduction in retinal photoreceptor cells. GCAP-2 activates retinal
guanylyl cyclases at low Ca2+ concentration (<100 nM) and inhibits them at
high Ca2+ (>500 nM). The light-induced lowering of the Ca2+ level from
approximately 500 nM in the dark to approximately 50 nM following illumination
is known to play a key role in visual recovery and adaptation. We report here
the three-dimensional structure of unmyristoylated GCAP-2 with three bound Ca2+
ions as determined by nuclear magnetic resonance spectroscopy of recombinant,
isotopically labeled protein. GCAP-2 contains four EF-hand motifs arranged in a
compact tandem array like that seen previously in recoverin. The root mean
square deviation of the main chain atoms in the EF-hand regions is 2.2 A in
comparing the Ca2+-bound structures of GCAP-2 and recoverin. EF-1, as in
recoverin, does not bind calcium because it contains a disabling Cys-Pro
sequence. GCAP-2 differs from recoverin in that the calcium ion binds to EF-4 in
addition to EF-2 and EF-3. A prominent exposed patch of hydrophobic residues
formed by EF-1 and EF-2 (Leu24, Trp27, Phe31, Phe45, Phe48, Phe49, Tyr81, Val82,
Leu85, and Leu89) may serve as a target-binding site for the transmission of
calcium signals to guanylyl cyclase.
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Figure 5.
Fig. 5. Schematic ribbon representation (A) and
space-filling model (B) of the energy-minimized average
structure of unmyristoylated GCAP-2 with three Ca^2+ bound. The
side chain atoms of residues at the domain interface (Ala^63,
Ala^67, Ile^103, and Ile^120) are shown in A and the color
scheme is as in Fig. 4. The figure was generated using Molscript
(49) and Raster3d (23).
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Figure 8.
Fig. 8. Space-filling representation (A) and
ball-and-stick model (B) of side chain atoms of the exposed
hydrophobic patch of GCAP-2. Hydrophobic, negatively charged,
and positively charged residues are highlighted in yellow, red,
and blue, respectively. Solvent-exposed hydrophobic residues
from EF-1 and EF-2 are indicated.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(1999,
274,
19329-19337)
copyright 1999.
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