The human peptide transporter 1 (PEPT1; SLC15A1) is expressed at a high level in enterocytes of the small intestine and in S1-segment of kidney proximal tubule cells. The PEPT1 has an enormous range of substrates including 400 dipeptides and 8000 tripeptides physiologically occurring. PEPT1 is a low affinity and high capacity transporter responsible for the rapid absorption of nutritional nitrogen sources as tri- or dipeptide originated from daily diet taken up orally, but also for several drugs. Furthermore, PEPT1 facilitates the renal reabsorption of peptides after glomerular filtration from the primary urine and rescues the important amino acid resource from the renal elimination to the urine. The driving force for the PEPT1 mediated uptake of peptides is a proton gradient (peptide/proton symporter).
Concentration dependent inhibition of hPEPT1-mediated Gly-Sar uptake by the probe inhibitor losartan