FIGURE 3.
The interaction between the PBD and LD peptides. a and b, overlay of GIT1 PBD spectra titrated with LD4 and LD2 peptides, respectively. Blue, GIT1 PBD alone; cyan, adding 0.5 eq of ligand; green, adding 1 eq of ligand; gold, adding 2 eq of ligand; red, adding 5 eq of ligand. Arrows mark significantly perturbed resonance, and dashed arrows mark perturbation with intermediate exchange rate. c, sequence alignment of human LD2 and LD4 peptides used in this study. Identical residues are marked with asterisks, and the LDXLLXXL motif is shown in bold. Conventional nomenclature is used; the first Leu is Φ0, and other residues are named as in the figure. d and e, composite chemical shift perturbation plotted against residue number for LD4 and LD2, respectively. Composite chemical shift perturbation was calculated by the equation Δδcomposite = (ΔδNH2 + ΔδN2/25)1/2. Lys663, Lys758, Gln, and Tyr751 are labeled, and they are among those dramatically shifted peaks.