Figure 1.

The roles of carnitine acyltransferase (CrAT) and carnitine in skeletal muscle mitochondria. (a) In physiological conditions, CrAT converts excessive acetyl‐coenzyme A (Ac‐CoA) to acetylcarnitine, and promotes its efflux out of mitochondria and cells. (b) In CrAT‐deficient conditions, Ac‐CoA is not converted to its permanent form, and is not excreted from mitochondria or cells. Excessive Ac‐CoA acts as an allosteric inhibitor of pyruvate dehydrogenase (PDH), a rate‐limiting enzyme for pyruvate entry into the tricarboxylic acid cycle, followed by impaired glucose utilization. Ac‐Cr, acetylcarnitine; T2DM, type 2 diabetes mellitus.