Schematic representation of the in situ permeabilization assay for metabolite profiling of palmitate β-oxidation in intact mitochondria. ACS, acyl-CoA synthetase; CACT, carnitine acylcarnitine translocase (officially named as SLC25A20); CPT1, carnitine palmitoyltransferase 1; CPT2, carnitine palmitoyltransferase 2; IMM, inner mitochondrial membrane; OMM, outer mitochondrial membrane; PM, plasma membrane.