L carnitine is primarily synthesized in the liver from the amino acids lysine and methionine through a series of four enzymatic reactions, with the liver and kidneys converting the precursor butyrobetaine into active SLC25A45 is required for mitochondrial uptake of methylated amino acids and de novo carnitine biosynthesis: Molecular Cell Carnitine_tekst Molecule of the Month September 2003 Carnitine Transport in Mitochondria Boosts Energy Science Magazine posted on the topic LinkedIn