Fatty acid binding proteins are small cytoplasmic lipid binding proteins that are expressed in a tissue specific manner. FABPs bind free fatty acids, cholesterol, and retinoids, and are involved in intracellular lipid transport. Circulating FABP levels are used as indicators of tissue damage. Some FABP polymorphisms have been associated with disorders of lipid metabolism and the development of atherosclerosis.
Fatty acid binding protein-6 (FABP6), also known as ileal bile acid binding protein (I-BABP) and gastrotropin, is a 15 kDa cytoplasmic protein that belongs to the FABP family. It is expressed in ileal epithelium and multiple other tissues. Alternate transcription promoters generate two transcript variants, encoding a 128 aa and a 177 aa residue protein. Human FABP6 isoform 2 contains 128 amino acid residues and is believed to be acetylated on Ala2. It binds both fatty acids and bile acids and has roles in fatty acid transport and metabolism. The amino acid sequence of human FABP6 is 80%, 78%, and 75% aa identical to that of mouse, canine, and porcine FABP6, respectively.