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Figure 3.
Figure 3. The structure of the ponsin SH3.2 domain in complex
with the paxillin PRR motif (SH3.2/paxillin PRR). (a) Overall
fold of the complex. The SH3 domain is shown in light blue
ribbon representation with the main residues of the interface
shown as sticks. The two main SH3 loops (RT and n-Src) are also
indicated. The paxillin polypeptide is depicted in orange
sticks. The orientation of the peptide is indicated by labeling
key residue positions (P[2], P[0], P[− 2]). (b) Electrostatic
potential representation of the SH3 domain in the same
orientation as shown in (a). The first hydrophobic loop is shown
on the left, while the third groove is flanked by two negatively
charged areas. The weighted (2F[o]–F[c]) electron density map
of the peptide computed with phases of the final model is also
shown. (c) 2D representation of the ponsin/paxillin interaction.
The panel was generated using LIGPLOT.^65 (d) Stick
representation of the main residues from ponsin (in yellow) and
paxillin (in orange) that participate in the binding interface.
(e) The specific conformations of the Asp835 and Glu839 for the
non-bound (cyan, two different conformations) and bound (light
blue) paxillin peptide in the RT loop. (f) Multiple sequence
alignment of the three SH3 domains of ponsin. The positions of
the secondary structural elements including the RT and n-Src
loops are indicated, as determined in the two crystal structures
of the SH3.2 domain. Residues involved in the binding interface
with the paxillin PRR peptide are shown in black boxes. Residues
in blue colour are conserved in two of the three domains and
additionally represented in lower case in the consensus line.
Residues that are similar are shown in red and additionally
capital letters in the consensus line (including also: ! anyone
of IV, $ anyone of LM, % anyone of FY, # anyone of NDQEBZ).
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