Monocarboxylate Transport Mechanisms in Cellular Metabolism

Monocarboxylate transporters (MCTs) are integral membrane proteins that mediate proton-coupled shuttling of small metabolites such as lactate, pyruvate and short-chain fatty acids across cellular membranes. Belonging to the solute carrier 16 (SLC16) family, MCT isoforms exhibit tissue-specific distribution and kinetic properties suited to the metabolic demands of different cell types. In highly glycolytic tissues and tumours, MCT1 and MCT4 facilitate lactate efflux to sustain glycolytic flux and prevent intracellular acidification, while in oxidative tissues these transporters support uptake of lactate for mitochondrial oxidation. Structural and functional studies have revealed how substrate binding sites and proton-coupling mechanisms confer specificity and directionality. Beyond classical monocarboxylates, some family members act on aromatic amino acids or oligopeptides, expanding the physiological remit of this transporter family. MCT activity is modulated by ancillary proteins such as basigin (CD147), which govern membrane localisation and stability. Dysregulation of monocarboxylate transport underpins a range of pathologies, from metabolic disorders and immune dysfunction to cancer progression, making MCTs attractive targets for therapeutic intervention. Recent advances in structural biology, genetic models and chemical probes have deepened our understanding of transport kinetics, regulatory interactions and pharmacological inhibition, paving the way for novel diagnostic and treatment strategies in metabolic disease and oncology.

Research from Nature Portfolio

Recent studies have uncovered an essential role for MCT1-mediated pyruvate transport in enabling epigenetic regulation of antibody production. In activated B cells, loss of MCT1 shifts metabolic flux from glycolysis towards oxidative phosphorylation, reducing pyruvate availability and impairing histone H3K27 acetylation required for antibody class-switch recombination. This work highlights how monocarboxylate flux couples cellular metabolism to chromatin modifications and immune function. Complementing these findings, high-resolution structural analysis of an SLC16 homologue in an outward-open conformation has elucidated key ligand binding sites and conformational transitions underlying L-lactate transport. Structure-based mutagenesis and functional assays have delineated the molecular basis of substrate recognition and proton coupling, offering a blueprint for rational design of isoform-selective inhibitors aimed at modulating lactate flux in pathological contexts such as tumour hypoxia and inflammation.

Monocarboxylate Transport Mechanisms in Cellular Metabolism publication trend

The graph below shows the total number of articles in monocarboxylate transport mechanisms in cellular metabolism across all publications each year (not limited to Nature Index journals).

Technical terms

Monocarboxylate transporter (MCT): A proton-coupled membrane protein that transports monocarboxylates such as lactate and pyruvate across biological membranes.

SLC16 family: A group of solute carrier proteins comprising multiple MCT isoforms with distinct substrate specificities and tissue distribution.

Glycolysis: A metabolic pathway that converts glucose to pyruvate, generating ATP and NADH in the cytosol.

Oxidative phosphorylation: Mitochondrial process in which electrons from NADH and FADH₂ drive ATP synthesis via the electron transport chain.

Histone H3K27 acetylation: An epigenetic mark on lysine 27 of histone H3 associated with active gene transcription.

Basigin (CD147): An ancillary glycoprotein required for proper membrane expression and function of certain MCT isoforms.

Synthetic lethality: A genetic interaction where perturbation of two genes leads to cell death, used to identify selective inhibitors in drug screening.

References

1. MCT1-governed pyruvate metabolism is essential for antibody class-switch recombination through H3K27 acetylation. Nature Communications (2024).
2. Paralog-dependent isogenic cell assay cascade generates highly selective SLC16A3 inhibitors. Cell Chemical Biology (2023).
3. Isolation of Functional Human MCT Transporters in Saccharomyces cerevisiae. Cells (2024).
4. Monocarboxylate Transporter 13 (MCT13/SLC16A13) Functions as a Novel Plasma Membrane Oligopeptide Transporter. Nutrients (2023).
5. Basigin (CD147) Is the Target for Organomercurial Inhibition of Monocarboxylate Transporter Isoforms 1 and 4 THE ANCILLARY PROTEIN FOR THE INSENSITIVE MCT2 IS EMBIGIN (gp70)*. Journal of Biological Chemistry (2005).
6. Mechanistic basis of L-lactate transport in the SLC16 solute carrier family. Nature Communications (2019).