MCTs mediate proton-coupled transport of monocarboxylates and ketone bodies Authored: Jassal, B, 2009-08-25 Edited: Jassal, B, 2009-08-21 Four members of the SLC16A gene family encode classical monocarboxylate transporters, MCT1-4. They all function as proton-dependent transporters of monocarboxylic acids such as lactate and pyruvate and ketone bodies such as acetacetate and beta-hydroxybutyrate. These processes are crucial in the regulation of energy metabolism and acid-base homeostasis.<br><br>SLC16A1 encodes MCT1, a ubiquitiously expressed protein (Garcia CK et al, 1994). Defects in SLC16A1 are the cause of symptomatic deficiency in lactate transport (SDLT), resulting in an acidic intracellular environment and muscle degeneration (Merezhinskaya N et al, 2000). Another defect in SLC16A1 causes exercise-induced hyperinsulinism (EIHI), a dominantly inherited hypoglycemic disorder characterized by inappropriate insulin secretion during anaerobic exercise or on pyruvate load (Otonkoski T et al, 2000). SLC16A7 encodes MCT2, a high affinity pyruvate transporter highly expressed in testis (Lin RY et al, 1998). SLC16A8 encodes MCT3 (Yoon H et al, 1999).<br><br>Human RPE (retinal pigment epithelial) cells express two proton-coupled monocarboxylate transporters: MCT1 in the apical membrane and MCT3 in the basolateral membrane. This suggested that the coordinated activities of these two transporters could facilitate the transepithelial transport of lactate from the retina to the choroid. (Philip NJ et al, 2003). Pubmed10493836 Pubmed10590411 Pubmed12657613 Pubmed17701893 Pubmed8124722 Pubmed9786900 Reactome Database ID Release 43433698 Reactome, http://www.reactome.org ReactomeREACT_20553 Reviewed: He, L, 2009-11-12 MCT substrates MCT substrates