The main fatty acid-binding protein in the liver of the shark (Halaetunus bivius) belongs to the liver basic type -: Isolation, amino acid sequence determination and characterization

Three fatty acid-binding proteins (FABPs) from the liver of the shark Halaetunus bivius were isolated and characterized: one of them belongs to the liver-type FABP family and the other two to the: heart-type FABP family. The complete primary structure of the first FABP, and partial primary structures of the two others, were determined. The liver-type FABP constitutes 69% of the total FABPs, and its amino acid sequence presents the highest identity with chicken, catfish, iguana and elephant fish liver basic FABPs. The L-FABP protein has low affinity for palmitic and oleic acids and high affinity for linoleic and arachidonic acids and other hydrophobic ligands, all of them important for the metabolic functions of the liver. In contrast, both heart-type FABPs have the highest affinity for palmitic acid, the principal fatty acid mobilized from fat deposits for beta-oxidation.