Solute Carrier Family 5, Member 12 (SLC5A12)

Normal blood lactate is maintained at about 1.5 mM, and little filtered lactate is excreted in urine. Reabsorption of lactate is mediated by the low-affinity Na(+)-coupled lactate transporter SLC5A12 in the initial part of the proximal tubule and by the high-affinity Na(+)-coupled lactate transporter SLC5A8 in the distal proximal tubule. The deduced 619-amino acid protein has 13 putative transmembrane domains, an exoplasmic N terminus, a cytoplasmic C terminus, 2 putative N-glycosylation sites, and several putative phosphorylation sites. Northern blot analysis detected 2 Slc5a12 variants in kidney and small intestine. RT-PCR also detected Slc5a12 expression in skeletal muscle. In situ hybridization showed predominant Slc5a12 expression in the early portions of mouse kidney proximal tubules and in the proximal portion of the intestinal tract.