Characterization of membrane transport mechanisms: a summary of the 1991 AASLD single topic conference

The membrane-associated 40 KD fatty acid binding protein (Berk's protein), a putative fatty acid transporter is present in human skeletal muscle

Muscle tissue (1.1 +/- 0.1 grams) was obtained from seven healthy individuals (3 males, 4 females) using an open incision approach before and after ingestion of either 75 grams of dextrose (N=5) or water (N=2). Purified sarcolemmal membranes from the muscle were prepared using a sucrose step gradient. A polyclonal antibody raised against the purified (99%) rat hepatocyte 40 KD membrane fatty acid binding protein (mFABP-L) was used to probe for this putative transporter in the muscle membranes using Western blot. A single band at the 40 KD MW band was identified which reacted antigenically with the protein purified from rat livers. These response of Berk's protein 60-75 minutes after dextrose ingestion (or water) was erratic and no specific trend could be identified. Our data demonstrate that the 40 KD mFABP-L originally isolated from rat liver is also present in human skeletal muscle membrane. This protein may be involved in transport of fatty acids across the membrane of skeletal muscle, however its physiological role in human fatty acid metabolism remains to be established.