Proton-coupled monocarboxylate transporter. Catalyzes the rapid transport across the plasma membrane of many monocarboxylates such as lactate, pyruvate, branched-chain oxo acids derived from leucine, valine and isoleucine, and the ketone bodies acetoacetate, beta-hydroxybutyrate and acetate. Depending on the tissue and on cicumstances, mediates the import or export of lactic acid and ketone bodies. Required for normal nutrient assimilation, increase of white adipose tissue and body weight gain when on a high-fat diet. Plays a role in cellular responses to a high-fat diet by modulating the cellular levels of lactate and pyruvate, small molecules that contribute to the regulation of central metabolic pathways and insulin secretion, with concomitant effects on plasma insulin levels and blood glucose homeostasis. Interacts with EMB; interaction mediates SLC16A1 targeting to the plasma membrane (By similarity). Interacts with isoform 2 of BSG; interaction mediates SLC16A1 targeting to the plasma membrane (PubMed:17127621, PubMed:25957687). Detected in heart and in blood lymphocytes and monocytes (at protein level). Widely expressed. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Overexpression in pancreatic beta-cells triggers insulin secretion in response to pyruvate, causing hyperinsulemia and hypoglycemia during strenuous exercise. Belongs to the major facilitator superfamily. Monocarboxylate porter (TC 2.A.1.13) family.