Interactions between Human Liver Fatty Acid Binding Protein and Peroxisome Proliferator Activated Receptor Selective Drugs

Figure 3

Binding to PPAR selective drugs protects L-FABP from limited proteolysis. (a) L-FABP was preequilibrated with increasing concentrations (0, 0.1, 0.4, 1.0, 5 μM) of GW7647 or L165,041 and then digested with trypsin. The resultant fragments were resolved on 20% polyacrylamide gels and visualized by Coomassie Blue G250 staining. Molecular weight standards are indicated on the ordinate. (b) The red spheres highlight the predicted tryptic cleavage hot spots on backbone overlays of the ensemble of structures determined by solution-state NMR for apo- (PDB code: 2PY1) and holo- (PDB code: 2L68) human L-FABP. (c) Top panel, tryptic cleavage sites predicted by the ExPASy PeptideCutter algorithm mapped onto the amino acid sequence of human L-FABP. The probability of cleavage at each site is indicated in parentheses. Bottom panel, the highest scoring sites (>90% probability) are mapped onto the crystallographic structure of human L-FABP (PDB code: 2F73).