 |
PDBsum entry 1fb8
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Signaling protein
|
PDB id
|
|
|
|
1fb8
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
|
|
|
|
* Residue conservation analysis
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Structural basis for discrimination of 3-Phosphoinositides by pleckstrin homology domains.
|
|
|
Authors
|
|
K.M.Ferguson,
J.M.Kavran,
V.G.Sankaran,
E.Fournier,
S.J.Isakoff,
E.Y.Skolnik,
M.A.Lemmon.
|
|
|
Ref.
|
|
Mol Cell, 2000,
6,
373-384.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
Pleckstrin homology (PH) domains are protein modules of around 120 amino acids
found in many proteins involved in cellular signaling. Certain PH domains drive
signal-dependent membrane recruitment of their host proteins by binding strongly
and specifically to lipid second messengers produced by agonist-stimulated
phosphoinositide 3-kinases (PI 3-Ks). We describe X-ray crystal structures of
two different PH domains bound to Ins(1,3,4,5)P4, the head group of the major PI
3-K product PtdIns(3,4,5)P3. One of these PH domains (from Grp1) is
PtdIns(3,4,5)P3 specific, while the other (from DAPP1/PHISH) binds strongly to
both PtdIns(3,4,5)P3 and its 5'-dephosphorylation product, PtdIns(3,4)P2.
Comparison of the two structures provides an explanation for the distinct
phosphoinositide specificities of the two PH domains and allows us to predict
the 3-phosphoinositide selectivity of uncharacterized PH domains.
|
|
|
|
|
|
|
|
Figure 1.
Figure 1. DAPP1-PH and Grp1-PH Recognize Distinct Patterns
of Phosphate Groups(A) Binding of Ins(1,3,4)P[3] (magenta,
squares), and Ins(1,5,6)P[3] (which has the same phosphate
arrangement as Ins(3,4,5)P[3]) (cyan, triangles) to DAPP1-PH
(left) and Grp1-PH (right) is compared using a
^3H-Ins(1,3,4,5)P[4] competition assay ([17]). DAPP1-PH binds
10-fold more strongly to Ins(1,3,4)P[3] than to the
Ins(3,4,5)P[3] analog, while the converse is true for
Grp1-PH.(B) Structures of the inositol trisphosphates.
Ins(1,3,4)P[3] (magenta) and Ins(3,4,5)P[3] (cyan) are
compared. Note that Ins(3,4,5)P[3] is equivalent to
Ins(1,5,6)P[3] except in the positioning of the single axial
hydroxyl group (2-OH). Ins(3,4,5)P[3] is not commercially
available, so Ins(1,5,6)P[3] was used for the experiment shown
in (A). Since Ins(3,5,6)P[3] and Ins(1,3,4)P[3] bind identically
to DAPP1-PH (Table 1), we suggest that the axial 2-hydroxyl is
not likely to be important in defining binding specificity.
|
|
Figure 6.
Figure 6. Prediction of PH Domain 3-Phosphoinositide
SpecificityPH domains shown to recognize PI 3-kinase products
([15]) are aligned with Grp1-PH and Btk-PH (A) or DAPP1-PH (B),
according to whether they are predicted (see text) to make
direct side chain contacts with the 5-phosphate of
Ins(1,3,4,5)P[4]. Elements of secondary structure are delineated
with gray arrows (β strands) or a black bar (the C-terminal α
helix). Residues are colored when their side chain is involved
in interactions with Ins(1,3,4,5)P[4] in the Btk-PH, Grp1-PH, or
DAPP1-PH complex structures. Yellow represents interaction with
the 1-phosphate; red, the 3-phosphate; green, the 4-phosphate;
and blue, the 5-phosphate. Color coding is predicted for PH
domains of unknown structure. The 3-phosphoinositide binding
motif ([15]) in the β1/β2 region is also color coded as
described above. In (A), PH domains with names underlined are
known to select PtdIns(3,4,5)P[3] over PtdIns(3,4)P[2]. Others
are predicted to do so. In (B), DAPP1-PH and PKB-PH are both
known to bind almost equally to PtdIns(3,4,5)P[3] and
PtdIns(3,4)P[2]. Others are predicted to do so.
|
|
|
|
|
|
The above figures are
reprinted
by permission from Cell Press:
Mol Cell
(2000,
6,
373-384)
copyright 2000.
|
|
|
|
|
|
|
