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PDBsum entry 1h10
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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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High-Resolution structure of the pleckstrin homology domain of protein kinase b/akt bound to phosphatidylinositol (3,4,5)-Trisphosphate.
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Authors
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C.C.Thomas,
M.Deak,
D.R.Alessi,
D.M.Van aalten.
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Ref.
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Curr Biol, 2002,
12,
1256-1262.
[DOI no: ]
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PubMed id
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Abstract
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The products of PI 3-kinase activation, PtdIns(3,4,5)P3 and its immediate
breakdown product PtdIns(3,4)P2, trigger physiological processes, by interacting
with proteins possessing pleckstrin homology (PH) domains. One of the best
characterized PtdIns(3,4,5)P3/PtdIns(3,4)P2 effector proteins is protein kinase
B (PKB), also known as Akt. PKB possesses a PH domain located at its N terminus,
and this domain binds specifically to PtdIns(3,4,5)P3 and PtdIns(3,4)P2 with
similar affinity. Following activation of PI 3-kinase, PKB is recruited to the
plasma membrane by virtue of its interaction with PtdIns(3,4,5)P3/PtdIns(3,4)P2.
PKB is then activated by the 3-phosphoinositide-dependent pro-tein kinase-1
(PDK1), which like PKB, possesses a PtdIns(3,4,5)P3/PtdIns(3,4)P2 binding PH
domain. Here, we describe the high-resolution crystal structure of the isolated
PH domain of PKB(alpha) in complex with the head group of PtdIns(3,4,5)P3. The
head group has a significantly different orientation and location compared to
other Ins(1,3,4,5)P4 binding PH domains. Mutagenesis of the basic residues that
form ionic interactions with the D3 and D4 phosphate groups reduces or abolishes
the ability of PKB to interact with PtdIns(3,4,5)P3 and PtdIns(3,4)P2. The D5
phosphate faces the solvent and forms no significant interactions with any
residue on the PH domain, and this explains why PKB interacts with similar
affinity with both PtdIns(3,4,5)P3 and PtdIns(3,4)P2.
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Figure 1.
Figure 1. Structure of PKB[α]PH Complexed to
Ins(1,3,4,5)P[4](A) A ribbon drawing of the
PKB[α]PH-Ins(1,3,4,5)P[4] complex, with the seven β strands
(labeled β1–7) shown in blue and the α helices (labeled
α1–2) shown in red. Ins(1,3,4,5)P[4] is shown as purple
carbons. The side chains of residues interacting with this
molecule are shown as gray carbons. The basic residues thought
to interact with the membrane have their side chains shown as
sticks with green carbons. The negatively charged residues on
VL2 that are hypothesized to interact with the kinase domain are
shown as gray-blue carbons.(B) Ribbon diagrams of the
Ins(1,3,4,5)P[4] binding sites of PKB, GRP1, DAPP1, and BTK. The
Ins(1,3,4,5)P[4] is shown as purple carbons. For the
PKB-Ins(1,3,4,5)P[4] structure, the experimental electron
density map from SOLVE after density modification is shown in
orange (contoured at 2.25σ). Residues that are hydrogen bonding
the ligand are shown as sticks with gray carbons. Hydrogen bonds
are shown as black dotted lines.
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Figure 2.
Figure 2. Charge DistributionElectrostatic surface
potential of PKB[α]PH-Ins(1,3,4,5)P[4] (calculated with GRASP),
with the molecule in the same orientation as in Figure 1. Blue
areas (+6kT) represent highly positively charged residues, and
the red areas (−6kT) represent highly negatively charged
residues. Ins(1,3,4,5)P[4] is shown as a stick model.
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The above figures are
reprinted
by permission from Cell Press:
Curr Biol
(2002,
12,
1256-1262)
copyright 2002.
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