Catalyzes the transfer of the acyl group of long-chain fatty acid-CoA conjugates onto carnitine, an essential step for the mitochondrial uptake of long-chain fatty acids and their subsequent beta-oxidation in the mitochondrion (PubMed:9691089, PubMed:11350182, PubMed:14517221). Plays an important role in hepatic triglyceride metabolism (By similarity). (R)-carnitine + hexadecanoyl-CoA = CoA + O-hexadecanoyl-(R)-carnitine Inhibited by malonyl-CoA. Lipid metabolism; fatty acid beta-oxidation. Homohexamer and homotrimer (By similarity). Identified in a complex that contains at least CPT1A, ACSL1 and VDAC1 (By similarity). Also identified in complexes with ACSL1 and VDAC2 and VDAC3 (By similarity). Strong expression in kidney and heart, and lower in liver and skeletal muscle. Up-regulated by fatty acids. A conformation change in the N-terminal region spanning the first 42 residues plays an important role in the regulation of enzyme activity by malonyl-CoA. The disease is caused by variants affecting the gene represented in this entry. Belongs to the carnitine/choline acetyltransferase family.