Peptide transporter 1 (PepT1) in fish: A review

The Peptide Transporter 1 (PepT1) plays an important role in animal protein nutrition. This is a low-affinity/high-capacity, stereoselective transmembrane transporter that mediates the uptake of a fraction of dietary amino acids in their di- and tripeptide forms. PepT1 is highly expressed in the intestines of vertebrates and the current studies examining PepT1 function have concentrated mostly on mammals and less emphasis has been placed on protein nutrition in fish. In the gastrointestinal track, amino acids are absorbed more efficiently in the form of small peptides than as free amino acids suggesting a potential role of PepT1 in the optimization of amino acid absorption which is relevant for fish nutrition. Therefore, this review focused on the physiological characteristics, structures, tissue distribution and expression of PepT1 transcripts and regulation of PepT1 protein in fish.