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PDBsum entry 3bbp
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Protein transport/splicing
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PDB id
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3bbp
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Contents |
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161 a.a.
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38 a.a.
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37 a.a.
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30 a.a.
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References listed in PDB file
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Key reference
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Title
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Rab and arl gtpase family members cooperate in the localization of the golgin gcc185.
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Authors
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A.S.Burguete,
T.D.Fenn,
A.T.Brunger,
S.R.Pfeffer.
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Ref.
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Cell, 2008,
132,
286-298.
[DOI no: ]
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PubMed id
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Abstract
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GCC185 is a large coiled-coil protein at the trans Golgi network that is
required for receipt of transport vesicles inbound from late endosomes and for
anchoring noncentrosomal microtubules that emanate from the Golgi. Here, we
demonstrate that recruitment of GCC185 to the Golgi is mediated by two
Golgi-localized small GTPases of the Rab and Arl families. GCC185 binds Rab6,
and mutation of residues needed for Rab binding abolishes Golgi localization.
The crystal structure of Rab6 bound to the GCC185 Rab-binding domain reveals
that Rab6 recognizes a two-fold symmetric surface on a coiled coil immediately
adjacent to a C-terminal GRIP domain. Unexpectedly, Rab6 binding promotes
association of Arl1 with the GRIP domain. We present a structure-derived model
for dual GTPase membrane attachment that highlights the potential ability of Rab
GTPases to reach binding partners at a significant distance from the membrane
via their unstructured and membrane-anchored, hypervariable domains.
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Figure 3.
Figure 3. Accessible Hydrophobic Residues in the Predicted
Coiled Coil Are Critical for Rab Binding
(A) Helical wheel
projection of a coiled coil predicted for GCC185 residues
1579–1606. Residues in registers “a–g” were predicted by
the Paircoil program. Residues at positions “a” and “d”
lie in the dimer interface. Boxed residues are candidates for
binding interactions with Rab GTPases.
(B and C) Effect of
alanine substitutions on Rab binding. Reactions contained
wild-type or mutant GST-C-110 ([B] 3 μM, [C] 2 μM) and
^35S-GTPγS-preloaded GTPases ([B] 170 pmol Rab9-His, [C] 190
pmol His-Rab6). Data are mean ± SD.
(D) Mass
determination of untagged RBD-87 I1588A/L1595A by multiple angle
static light scattering. The gel filtration elution profile of
the protein (black line) and molecular mass (gray line) are
shown. Polydispersity of the peak was 1.001.
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Figure 4.
Figure 4. Structure of the Rab6-GCC185 Complex
(A)
Ribbon representation of the GCC185 Rab-binding domain dimer
(green) and Rab6 (blue) bound to GTP (stick model) and magnesium
(sphere). Switch I and II regions of Rab6 (Chattopadhyay et al.,
2000) are colored yellow and orange respectively.
(B) View
of the Rab6-GCC185-binding interface. A single GCC185 helix (E)
out of the two-fold symmetric coiled coil is shown for clarity.
Each helix contacts switch regions from two opposed Rab6
molecules A and B. Rab6 switch I and II (including W67) are
colored yellow and orange, respectively. Protein backbone
(α-carbon trace) and side chains involved in polar and
hydrophobic interactions are shown. Carbonyl oxygens are shown
for A44, I48, and I1588, and C-Cα bonds have been added to
simplify the figure. An anomalous difference Fourier density map
of the selenomethionine-substituted crystal (pink, contoured at
6σ) is shown for GCC185.
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The above figures are
reprinted
from an Open Access publication published by Cell Press:
Cell
(2008,
132,
286-298)
copyright 2008.
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