The Fatty Acid-Binding Proteins (FABPs) are a family of proteins that areprincipally located in the cytosol and are characterised by the ability tobind to hydrophobic ligands, such as fatty acids, retinol, retinoic acid, bile salts and pigments [<cite idref="PUB00000681"/>, <cite idref="PUB00003644"/>]. Recently, a number of family members havebeen identified that are secreted, such as gastrotropin and mammary-derivedgrowth inhibitor. The family is implicated in general lipid metabolism,acting as intracellular transporters of hydrophobic metabolic intermediatesand as carriers of lipids between membranes [<cite idref="PUB00000681"/>, <cite idref="PUB00003644"/>, <cite idref="PUB00003643"/>]. The FABPs exhibit a high degree both of sequence and structural similarity.They are small, 12-18 kDa, soluble proteins composed of 110-160 residues. Their crystal structures show them to be 10-stranded anti-parallel beta-barrels with a +1,+1 topology, which wrap around an internal cavity to form a ligand binding site [<cite idref="PUB00003644"/>, <cite idref="PUB00003643"/>]. Ligand specificity and affinity is governed by the side chains of amino acids that extend into the cavity, especially the polar residue that interacts through hydrogen bonding and electrostatic interactions with the polar head group of the ligand [<cite idref="PUB00027738"/>]. An arginine or a glutamine residue is used for binding fatty acids or retinoids, respectively. The anti-parallel beta-barrel fold is also exploited by the lipocalins, which function similarly by binding smallhydrophobic molecules. Similarity at the sequence level, however, is lessobvious, being confined to a single short N-terminal motif. Cytosolic fatty-acid binding