ペプチドトランスポーターの分子栄養学

The oligopeptide transporter (PepT 1), which is located in the intestinal brush border membrane, provides a major mechanism for protein absorption in the small intestine. Molecular cloning of the gene encoding rat PepT 1 has predicted a 78,710 -kilodalton protein consisting of 710 amino acid residues and processing 12 putative membrane-spanning domains. The characterization of its function has shown that (1) it transports dipeptides, tripeptides, and β-lactam antibiotics but not free amino acids or peptides with more than four amino acid residues, and (2) its driving force for uphill transport requires proton binding. A human intestinal cell line (Caco-2) has been used to investigate the molecular regulation of the PepT 1 gene. These studies suggest that amino acids directly stimulate the promoter activity of the PepT 1 gene. Thus, PepT 1 plays important roles in nutritional and pharmacological therapies.