MONOCARBOXYLIC ACID TRANSPORTERS

Monocarboxylate transporters (or MCTs) are widely distributed in the body and responsible for the uptake of short-chain monocarboxylates, hormones, nutrients, amino acids, as well as xenobiotics. In total, there are 14 isoforms of the MCT family (MCTs 1–14, SLC16A1–14 ), with MCTs 1–4 extensively characterized as proton-dependent transporters with a critical role in the transport of products of the glycolysis cycle (i.e., lactate and pyruvate), as well as ketone bodies, across plasma membranes. The other MCTs 5–14 have not been extensively evaluated; however, their substrate specificities have more recently begun to be characterized. Monocarboxylate substrates are also transported by two members of the SLC5A family in a sodium-dependent manner, namely, SMCT1 ( SLC5A8 ) and SMCT2 ( SLC5A12 ). This review will provide a summary of the current literature focusing on the characterization, function, and regulation of the monocarboxylate transporters, and on their roles in drug disposition and in health and disease.