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PDBsum entry 1k3a
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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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Structure and autoregulation of the insulin-Like growth factor 1 receptor kinase.
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Authors
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S.Favelyukis,
J.H.Till,
S.R.Hubbard,
W.T.Miller.
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Ref.
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Nat Struct Biol, 2001,
8,
1058-1063.
[DOI no: ]
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PubMed id
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Abstract
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The insulin-like growth factor 1 (IGF1) receptor is closely related to the
insulin receptor. However, the unique biological functions of IGF1 receptor make
it a target for therapeutic intervention in human cancer. Using its isolated
tyrosine kinase domain, we show that the IGF1 receptor is regulated by
intermolecular autophosphorylation at three sites within the kinase activation
loop. Steady-state kinetic analyses of the isolated phosphorylated forms of the
IGF1 receptor kinase (IGF1RK) reveal that each autophosphorylation event
increases enzyme turnover number and decreases Km for ATP and peptide. We have
determined the 2.1 A-resolution crystal structure of the tris-phosphorylated
form of IGF1RK in complex with an ATP analog and a specific peptide substrate.
The structure of IGF1RK reveals how the enzyme recognizes peptides containing
hydrophobic residues at the P+1 and P+3 positions and how autophosphorylation
stabilizes the activation loop in a conformation that facilitates catalysis.
Although the nucleotide binding cleft is conserved between IGF1RK and the
insulin receptor kinase, sequence differences in the nearby interlobe linker
could potentially be exploited for anticancer drug design.
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Figure 2.
Figure 2. Overall structure of IGF1RK and activation loop
interactions. a, Ribbon diagram of the IGF1RK structure.  -strands
(numbered) are shown in cyan;  -helices
(lettered), in red. The peptide is colored orange with the
phosphate-acceptor Tyr shown in ball-and-stick representation.
The nucleotide analog, AMP-PCP, is also shown in ball-and-stick
representation (black). The dashed gray coil represents the
disordered portion of the kinase insert. The N-terminal (NT) end
of the structure is labeled. The C-terminal end is after J,
hidden behind 8.
b, Interactions within the A-loop (in stereo). The A-loop
(residues 1,123 -1,145) is shown as a backbone worm (green) with
side chains of selected residues shown in stick representation
(carbon = green, nitrogen = blue, oxygen = red, sulfur = yellow
and phosphorus = black). Residues contributing to stabilization
of the activation loop via hydrophobic interactions are shown
with a molecular surface. Hydrogen bonds are shown as dashed
lines (black). c, Interactions between the A-loop and other
kinase segments (in stereo). A backbone worm representation is
shown for the A-loop (green), a segment including part of the
catalytic loop (residues 1,100 -1,105 in orange) and a segment
corresponding to 12
(residues 1,157 -1,159 in gray). Side chain and main chain atoms
are shown in stick representation with the same color scheme as
in (b) with the exception of carbon, which is colored the same
as the corresponding backbone worm. For clarity, pTyr 1136 has
been omitted.
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Figure 3.
Figure 3. IGF1RK peptide substrate binding and comparison to
IRK. a, Stereo view of the 2F[o] - F[c] electron density map
(2.1 Å resolution, 1  contour)
for the peptide substrate. The electron density is shown as a
wire mesh (blue); the peptide substrate (orange), in stick
representation. b, Stereo view of interactions at the IGF1RK
-peptide substrate interface. A semitransparent molecular
surface (gray) of IGF1RK is shown with residues (labeled and
displayed in stick representation) that define the peptide
binding cleft and interact with the peptide substrate. The
peptide (shown in stick representation) is illustrated without a
molecular surface, with residues labeled relative to the
phosphate acceptor Tyr (P0). Hydrogen bonds between the peptide
and the enzyme are shown as black lines. Bond coloring is carbon
= orange, oxygen = red, nitrogen = blue, sulfur = green and
phosphorus = yellow. c, A molecular surface representation of
IGF1RK illustrating surface residue differences between IGF1RK
and IRK. The molecular surface contributed by differing side
chains between the two structures are colored green. The
molecular surface contributed by the Thr 1053 side chain in the
interlobe linker is colored yellow (see text). d, A backbone
worm representation of IGF1RK. Segments corresponding to
residues that differ between IGF1RK and IRK are colored green.
In (c,d), stick representations of the nucleotide analog
(AMP-PCP) and peptide are shown. The semitransparent segment
represents the portion of the kinase insert disordered in the
structure. Bond coloring is the same as in (a).
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Biol
(2001,
8,
1058-1063)
copyright 2001.
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