ON THE MOLECULAR-ORIGIN OF CHARGE HETEROGENEITY OF RAT-LIVER FATTY-ACID-BINDING PROTEIN (Z-PROTEIN)

The occurrence of many charge isoforms is known for rat liver fatty ac id-binding protein, and this is the major cause of conflicting data on the characterization of the protein. Recently, M. Li and T. Ishibashi (1992, Arch. Biochem. Biophys. 298, 254-258) clearly demonstrated tha t some charge isoforms are due to bound fatty acids. We found that aci dic fraction (DE-III) of rat liver fatty acid-binding protein containe d isoaspartyl-105 protein resulted from deamidation and peptide rearra ngement at Asn-105. Since DE-III fraction carries mainly arachidonate, this post-translational modification might modulate binding specifici ty of fatty acid-binding protein. (C) 1994 Academic Press, Inc.