ILBP Background Information The fatty acid binding protein (FABP) family of cytoplasmic hydrophobic ligand binding proteins influence lipid metabolism by binding and transporting long-chain fatty acids. Ileal lipid binding protein (ILBP) is a cytosolic ileocyte FABP that binds to both bile acids and fatty acids thereby mediating active uptake of bile acid in the ileum. Transport of bile acids from the liver is essential for the solubilization and transport of dietary lipids. ILBP contains ten antiparallel b strands arranged in two nearly orthogonal b sheets (b clam shell), covered on one side by two short, nearly parallel a helices. Binding of fatty acids or bile acids to ILBP alters the side-chain proton resonances of amino acids within the protein cavity and increases the affinity of ILBP for bile acids; bile acid binding to ILBP is a positive-feedback regulation mechanism. The human ILBP gene maps to position 5q35, with transcript being abundant in the small intestine.
