It transports sodium cations (i.e., Na+) in association with the anionic forms (see conjugated base) of certain short-chain fatty acids (i.e., SC-FAs) and other agents through the plasma membrane from the outside to the inside of cells.
[1] The only other member of the sodium-coupled monocarboxylate transporter group (sometimes referred to as the SLC5A family[2]), SMCT1, similarly co-transports SC-FAs and other agents into cells.
These SC-FAs serve as energy sources for[8] and activators of diverse responses in[9][10][11] a wide range of cell types in the intestinal wall and throughout the entire body.
[13] The SC-FAs transported into cells by SMCT2 include butyric, proprionic, pyruvic, lactic, acetic, and β-hydroxybutyric acids.
SMCT1 likewise transports these SC-FAs and nicotinic acid and is blocked by the cited anti-inflammatory drugs.
Cells bearing the SMCT1 transporter, which has a relatively high affinity for the SC-FAs, are located in the large intestine and cecum.
)[10][11][16] In addition, the SC-FAs that enter cells can directly activate certain signal transduction pathways and thereby elicit cellular responses independently of the three cited SC-FA receptors.
They form and maintain the retina's structure, control retinal immune responses by, e.g., releasing inflammatory mediators and engulfing dead cell debris, and provide retinal neurons with essential nutrients, particularly the SC-FA, pyruvic acid.
The transfer of lactic acid out and into human skeletal muscle has been thought to be mediated by the H+-coupled monocarboxylate transporters, MCT1 and MCT4.