MCT1

Monocarboxylate transporter 1 (MCT1) also known as solute carrier family 16 member 1 (SLC16A1). The major physiological role of MCT1 is to facilitate lactic acid entry into or efflux out of cells depending on their metabolic state. In liver parenchymal cells and the proximal convoluted tubule cells of the kidney, MCT1 may be used to transport L-lactate into the cells for gluconeogenesis for which it is a major substrate, especially after exercise. In the heart and red skeletal muscle, MCT1 is required for lactate and ketone bodies to enter the myocytes and be oxidized as a major respiratory fuel under conditions when their concentrations are elevated. Indeed, in skeletal muscle, there is a strong correlation between the amount of MCT1 expressed in muscle fibers and their oxidative capacity (mitochondrial content.MCT1 also facilitates the transport of these same monocarboxylates across the blood brain barrier for uptake into neurons (via MCT1 or MCT2) which, like red skeletal muscle, use them as respiratory fuels. In both muscle and the brain, there is cooperation between MCT isoforms involved in lactic acid efflux and influx by different cell types within the same tissue.