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PDBsum entry 2pfv
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Endocytosis/exocytosis
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PDB id
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2pfv
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References listed in PDB file
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Key reference
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Title
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The crystal structure of mouse exo70 reveals unique features of the mammalian exocyst.
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Authors
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B.A.Moore,
H.H.Robinson,
Z.Xu.
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Ref.
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J Mol Biol, 2007,
371,
410-421.
[DOI no: ]
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PubMed id
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Abstract
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The exocyst is a eukaryotic tethering complex necessary for the fusion of
exocytic vesicles with the plasma membrane. Its function in vivo is tightly
regulated by interactions with multiple small GTPases. Exo70, one of the eight
subunits of the exocyst, is important for the localization of the exocyst to the
plasma membrane. It interacts with TC10 and Rho3 GTPases in mammals and yeast,
respectively, and has been shown recently to bind to the actin-polymerization
complex Arp2/3. Here, we present the crystal structure of Mus musculus Exo70 at
2.25 A resolution. Exo70 is composed of alpha-helices in a series of
right-handed helix-turn-helix motifs organized into a long rod of length 170 A
and width 35 A. Although the alpha-helical organization of this molecule is
similar to that in Saccharomyces cerevisiae Exo70, major structural differences
are observed on the surface of the molecule, at the domain boundaries, and in
various loop structures. In particular, the C-terminal domain of M. musculus
Exo70 adopts a new orientation relative to the N-terminal half not seen in S.
cerevisiae Exo70 structures. Given the low level of sequence conservation within
Exo70, this structure provides new insights into our understanding of many
species-specific functions of the exocyst.
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Figure 1.
Figure 1. A stereo cartoon diagram of MmExo70 is shown.
Residues are shown in color: N domain, red; M domain, yellow;
and C domain, blue. The α-helices are drawn as coils and
labeled from H1 to H19; turns and loops, solid tubes; unobserved
residues, broken lines (no β strands are observed in the
structure).
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Figure 2.
Figure 2. Structural alignment of Exo70 in M. musculus, H.
sapiens, D. melanogaster, S. pombe, and S. cerevisiae. Invariant
residues are shaded purple. Similar but not identical residues
are shaded pink. Secondary structural elements are indicated
above the sequence block for MmExo70 and below for ScExo70:
α-helices, rectangles; other elements, continuous lines;
structurally unobserved residues, broken lines. For MmExo70: N
domain, red; M domain, yellow; and C domain, blue (same as
Figure 1). For ScExo70: N domain, brown; M domain, green; and C
domain, cyan. For clarity, sequences lacking homology or
unobserved in the structures have been replaced with bracketed
numbers indicating the number of residues omitted.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2007,
371,
410-421)
copyright 2007.
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