ACYL-COA-BINDING PROTEIN (ACBP) CAN MEDIATE INTERMEMBRANE ACYL-COA TRANSPORT AND DONATE ACYL-COA FOR BETA-OXIDATION AND GLYCEROLIPID SYNTHESIS

The dissociation constants for octanoyl-CoA, dodecanoyl-CoA and hexadecanoyl-CoA binding to acyl-CoA-binding protein (ACBP) were determined by using titration microcalorimetry. The K-D values obtained, (0.24 +/- 0.02) x 10(-6) M, (0.65 +/- 0.2) x 10(-8) M and (0.45 +/- 0.2) x 10-(13) M respectively, were much lower than expected. ACBP was able to extract hexadecanoyl-CoA from phosphatidylcholine membranes immobilized on a nitrocellulose membrane. The acyl-CoA/ACBP complex formed was able to transport acyl-CoA to mitochondria or microsomes in suspension, or to microsomes immobilized on a nitrocellulose membrane, and to donate them to beta-oxidation or glycerolipid synthesis in mitochondria or microsomes, respectively.