Studies of plasma membrane fatty acid-binding protein and other lipid-binding proteins in human skeletal muscle

Abstract

The first putative fatty acid transporter identified was plasma membrane fatty acid-binding protein (FABP pm). Later it was demonstrated that this protein is identical to the mitochondrial isoform of the enzyme aspartate aminotransferase. In recent years data from several cell types have emerged, indicating that FABP pm plays a role in the transport of long-chain saturated and unsaturated fatty acids. In the limited number of studies in human skeletal muscle it has been demonstrated that dietary composition and exercise training can influence the content of FABP pm. Ingestion of a fat-rich diet induces an increase in FABP pm protein content in human skeletal muscle in contrast to the decrease seen during consumption of a carbohydrate-rich diet. A similar effect of a fat-rich diet is also observed for cytosolic fatty acid-binding protein and fatty acid translocase/CD36 protein expression. Exercise training up regulates FABP pm protein content in skeletal muscle, but only in male subjects; no significant differences were observed in muscle FABP pm content in a cross-sectional study of female volunteers of varying training status, even though muscle FABP pm content did not depend on gender in the untrained state. A higher utilization of plasma long-chain fatty acids during exercise in males compared with females could explain the gender-dependent influence of exercise training on FABP pm. The mechanisms involved in the regulation of the function and expression of FABP pm protein remain to be clarified.