Muscle palmitate uptake and binding are saturable and inhibited by antibodies to FABPPM

• Published in: Molecular and cellular biochemistry 2000-07, Vol.210 (1-2), p.53
• Main Authors: Turcotte, Lorraine P, Swenberger, Jason R, Tucker, Michelle Z, Tee, Alice J, Trump, Gary, Luiken, Joost Jfp, Bonen, Arend
• Format: Article
• Language: English
• Subjects: Fatty acids; Muscles; Proteins
• ISSN: 0300-8177; 1573-4919
• DOI: 10.1023/A:1007046929776

Studies show that uptake of long-chain fatty acids (LCFA) across the plasma membranes (PM) may occur partly via a carrier-mediated process and that the plasma membrane fatty acid-binding protein (FABP^sub PM^) may be a component of this system. To test the hypothesis that FABP^sub PM^ is involved in transsarcolemmal transport of LCFA in muscle, we measured palmitate uptake in giant sarcolemmal vesicles and palmitate binding to PM proteins in rat muscles, (1) in the presence of increasing amounts of unbound palmitate and (2) in the absence or presence of antibody to FABP^sub PM^. Both palmitate uptake and binding were found to be saturable functions of the unbound palmitate concentration with calculated V^sub max^ values of 10.5 ± 1.2 pmol/mg protein/15 sec and 45.6 ± 2.9 nmol/mg protein/15 min and K^sub m^ values of 12.8 ± 3.8 and 18.4 ± 1.8 nmol/L, respectively. The V^sub max^ values for both palmitate uptake and binding were significantly decreased by 75-79% in the presence of a polyclonal antibody to the rat hepatic FABP^sub PM^. Antibody inhibition was found to be dose-dependent and specific to LCFA. Glucose uptake was not affected by the presence of the antibody to FABP^sub PM^. Palmitate uptake and binding were also inhibited in the presence of trypsin and phloretin. These results support the hypothesis that transsarcolemmal LCFA transport occurs in part by a carrier-mediated process and that FABP^sub PM^ is a component of this process in muscle.[PUBLICATION ABSTRACT]