Structural and biochemical characterization of the lungfish (Lepidosiren paradoxa) liver basic fatty acid binding protein

Only one fatty acid-binding protein (FABP) from the liver of the lungfish ( Lepidosiren paradoxa) was isolated and characterized. The sequence comparis on of lungfish FABP with that of the known members of the liver FABP (L-FAB P) and liver basic FABP (Lb-FABP) subfamilies indicates that it is more clo sely related to chicken, iguana, frog, axolotl, catfish, and shark Lb-FABPs than to mammalian and axolotl L-FABPs. Lungfish liver expression of this s ingle Lb-FABP contrasts with the other fish studied so far which coexpress an Lb-FABP with heart-adipocyte and/or intestinal FABP types. The lungfish liver FABP expression pattern resembles that of tetrapods, which only expre sses liver type FABPs. Lungfish Lb-FABP is one of the two FABPs reported to have a disulfide bridge. The molecular modeling of lungfish Lb-FABP predic ts that nine of the conserved residues of Lb-FABPs are oriented toward the binding cavity, thus suggesting they are related to the protein binding cha racteristics. (C) 2001 Academic Press.