Species specificity profiling of rat and human organic cation/carnitine transporter Slc22a5/SLC22A5 (Octn2/OCTN2)

l-Carnitine and Acetyl-l-carnitine Roles and Neuroprotection in Developing Brain

“…There are also dietary supplements containing the L-isomer (L-carnitine) with high purity [42]. L-Carnitine and its corresponding derivative containing 2 carbons in the acyl moiety (acetyl-L-carnitine) are taken up into cells via the organic cation transporter novel 2 (OCTN2) which cotransports L-carnitine with Na + [43, 44]. Uptake into brain also occurs primarily via the OCTN2 transporter [1, 44, 45].…”

“…While medium- and short-chain fatty acids can freely enter mitochondria by diffusion through the membranes [1], L-carnitine has an essential role in the transfer of activated long chain fatty acids into the mitochondria in a series of reactions called the “carnitine shuttle”, so that they can undergo β-oxidation (Figure 2) [1, 43]. The enzyme acyl-CoA synthase converts long chain fatty acids to fatty acyl-CoAs, which are subsequently converted to acylcarnitines by the enzyme carnitine palmitoyltransferase I (CPT I) localized in the outer mitochondrial membrane [1, 43].…”

“…The enzyme acyl-CoA synthase converts long chain fatty acids to fatty acyl-CoAs, which are subsequently converted to acylcarnitines by the enzyme carnitine palmitoyltransferase I (CPT I) localized in the outer mitochondrial membrane [1, 43]. Acylcarnitines cross the inner mitochondrial membrane via a transporter, the carnitine/acylcarnitine translocase, in exchange for free L-carnitine [1, 43].…”

“…The enzyme acyl-CoA synthase converts long chain fatty acids to fatty acyl-CoAs, which are subsequently converted to acylcarnitines by the enzyme carnitine palmitoyltransferase I (CPT I) localized in the outer mitochondrial membrane [1, 43]. Acylcarnitines cross the inner mitochondrial membrane via a transporter, the carnitine/acylcarnitine translocase, in exchange for free L-carnitine [1, 43]. The enzyme carnitine palmitoyltransferase II (CPT II) which is localized in the inner mitochondrial membrane converts acylcarnitines back to acyl CoAs and free L-carnitine, which exits the mitochondria and serves as the substrate for CPT I to form more acylcarnitine [1, 43].…”

“…Acylcarnitines cross the inner mitochondrial membrane via a transporter, the carnitine/acylcarnitine translocase, in exchange for free L-carnitine [1, 43]. The enzyme carnitine palmitoyltransferase II (CPT II) which is localized in the inner mitochondrial membrane converts acylcarnitines back to acyl CoAs and free L-carnitine, which exits the mitochondria and serves as the substrate for CPT I to form more acylcarnitine [1, 43]. Therefore, the transfer of acyl moieties from fatty acyl-CoA esters to carnitine also replenishes intracellular free CoA that is crucial for intermediary metabolism [53].…”