|
Figure 1.
FIG. 1. Crystal structure of the talin FERM F3-PIPKI  interaction. A, surface
representation of talin FERM F3 domain colored by electrostatic
potential (red for -6 kT/e and blue for 6 kT/e) with the PIPKI
ligand, residues
641-649, shown as sticks. Trp-642 (W642) in the PIPKI sequence
(which is critical for binding) binds into a deep pocket on the
surface of F3. The SPLH sequence adopts the same reverse-turn
conformation as the classic NPXY motif. Thus, serine plays a
similar role as that of asparagine, forming an N-cap to the
reverse turn; the proline promotes the reverse turn, the leucine
packs against the hydrophobic surface of F3, and the histidine
takes the place of the tyrosine or phenylalanine found in the
integrins, packing against a flat somewhat acidic surface. B,
comparison of PIPKI (yellow) and integrin
 3
(light green) sequences bound to talin FERM F3 (ribbon
representation in blue). The 3 structure was
superposed by aligning the conserved C  atoms of the talin FERM
F3 domain of the talin-PIPKI and talin- 3
complexes. PIPKI and 3 residues are labeled
in red and green respectively. C, detailed stereo view of the
talin-PIPKI interaction. Talin
residues involved in the interaction are shown in gray, and the
PIPKI ligand is shown in
yellow. Intramolecular and intermolecular H-bonds are shown as
dotted lines. Surface electrostatic potential was calculated
with the program APBS (30). Molecular representation figures
were generated with the programs MOLSCRIPT (31, 32), RASTER3D
(32), and PyMol (http://www.pymol.org). Single letter amino acid
abbreviations are used with position numbers.
|
