Monocarboxylate transporter (MCT) family of the Major Facilitator Superfamily of transporters
The animal Monocarboxylate transporter (MCT) family is also called Solute carrier family 16 (SLC16 or SLC16A). It is composed of 14 members, MCT1-14. MCTs play an integral role in cellular metabolism via lactate transport and have been implicated in metabolic synergy in tumors. MCT1-4 are proton-coupled transporters that facilitate the transport across the plasma membrane of monocarboxylates such as lactate, pyruvate, branched-chain oxo acids derived from leucine, valine and isoleucine, and ketone bodies such as acetoacetate, beta-hydroxybutyrate and acetate. MCT8 and MCT10 are transporters which stimulate the cellular uptake of thyroid hormones such as thyroxine (T4), triiodothyronine (T3), reverse triiodothyronine (rT3) and diidothyronine (T2). MCT10 also functions as a sodium-independent transporter that mediates the uptake or efflux of aromatic acids. Many members are orphan transporters whose substrates are yet to be determined. The MCT family belongs to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
Feature 1:putative chemical substrate binding pocket [chemical binding site]
Evidence:
Comment:based on the structures of MFS transporters with bound substrates, substrate analogs, and/or inhibitors
Comment:since MFS proteins facilitate the transport of many different substrates including ions, sugar phosphates, drugs, neurotransmitters, nucleosides, amino acids, and peptides, the residues involved in substrate binding may not be strictly conserved among superfamily members
Comment:the substrate binding site or translocation pore has access to both sides of the membrane in an alternating fashion through a conformational change of the MFS transporter
Jiyao W et al.(2023). "The conserved domain database in 2023.",