Carnitine-acylcarnitine translocase acts as an inner membrane exchange transpoer. Carnitine is synthesized from:

Levocarnitine (L-carnitine): It is an endogenous carboxylic acid that facilitates transpo of long-chain fatty acids into mitochondria for beta-oxidation and prevents intracellular accumulation of toxic acyl-CoA. L-Carnitine is ubiquitous in diets rich in meats and dairy products and is also synthesized in the body from the amino acids lysine and methionine. Valproic acid causes carnitine deficiency, resulting in mitochondrial dysfunction. Primary defects of carnitine transpo may manifest as Reyes syndrome, cardiomyopathy, or skeletal myopathy with hypotonia. Ref: Thomas J.A., Van Hove J.L. (2012). Chapter 36. Inborn Errors of Metabolism. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.