Fig. 2
Binding specificity of paxillin LD motifs for the two FAT binding sites. (A) Crystal structures of paxillin LD2 and LD4 peptides bound to FAT [21]. At high peptide concentrations used for crystallization both LD motifs can bind FAT via two binding sites, one involving helices H1 and H4 (H14), the other via H2 and H3 (H23). Due to crystal packing the two sites are occupied on different FAT molecules, which are superimposed here. Side chains of residues mutated in H14 and H23 are colored red; the side chain of Y925 is colored yellow. (B-E) Binding curves for peptides LD1 (B), LD2 (C), LD4 (D) and LD2/4 (E) to FAT-WT or FAT mutated at LD binding sites H14 or H23 or both (H14-23). Apparent KD values are obtained from fitting a one-site binding model. Resulting KD values with an error > 25% are considered not determined (ND). Error bars represent SD from 4 measurements