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Figure 1.
Figure 1. NMR structures of the cis and trans Itk SH2
conformers. a, Stereo view of 20 low energy structures of the
cis (coral) and trans (turquoise) conformations of the Itk SH2
domain. Backbone heavy atoms within the secondary structural
elements over the entire sequence were used for superpositions.
b, Ribbon diagrams of the energy minimized average structures of
the cis (left) and trans (right) conformers. Secondary
structural elements and ligand-binding pockets are labeled in
(a,b) according to standard nomenclature for SH2 domains8. Pro
287 is labeled in each structure. c, Sequence of the Itk SH2
domain and sequence alignment of the CD loop regions in the SH2
domains of several tyrosine kinases. The residues that give rise
to nondegenerate chemical shifts2 are bold and underlined, and
Pro 287 is labeled. d, Solvent-accessible surface plot of the
cis conformer. The residues that give rise to dual resonances
because of Pro cis-trans isomerization are highlighted in white.
The trans conformer shows a similar contiguous surface for the
heterogeneous residues (data not shown). e, Overlay of the
energy minimized average structures of the cis (coral) and trans
(turquoise) conformers. Expanded views of the CD loop (left),
the central  -sheet
(right) and the BG loop regions (middle) are shown. All
structures are rendered using MolMol31.
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