The peptide transporter 1 (PepT1), encoded by the SLC15A1 gene, is a low-affinity, high-capacity proton-coupled symporter responsible for the uptake of dipeptides, tripeptides, and a broad range of peptide-like drugs across the plasma membrane. PepT1 is primarily expressed in the small intestine, where it supports nutrient absorption and contributes to the oral bioavailability of many therapeutic compounds, including β-lactam antibiotics and ACE inhibitors. By mediating proton-dependent peptide transport, PepT1 plays a central role in intestinal physiology, nutrient homeostasis, and drug pharmacokinetics.