2.A.17.4.8
Solute carrier family 15 member 2 (Kidney H⁺:peptide cotransporter) (Oligopeptide transporter, kidney isoform) (Peptide transporter 2, PEPT2) (Verri et al. 2016). Transports opioid peptides (Ganapathy and Miyauchi 2005). It is an electrogenic uphill peptide and peptidomimetic drug transporter, coupling of substrate translocation to a transmembrane electrochemical proton gradient serving as the driving force. In human airways, PEPT2 is localized to bronchial epithelium and alveolar type II pneumocytes, and transport studies revealed that both peptides and peptidomimetic drugs such as antibiotic, antiviral, and antineoplastic drugs are carried by the system. PEPT2 is also responsible for the transport of delta-aminolevulinic acid, which is used for photodynamic therapy and the diagnostics of pulmonary neoplasms (Groneberg et al. 2004). PepT2 in mammals plays essential roles in the reabsorption and conservation of peptide-bound amino acids in the kidney and in maintaining neuropeptide homeostasis in the brain. It is also responsible for the absorption and disposing of peptide-like drugs, including angiotensin-converting enzyme inhibitors, β-lactam antibiotics and antiviral prodrugs. Understanding the structure, function and regulation of PepT2 is of emerging interest in nutrition, medical and pharmacological research. Wang et al. 2022 provided an overview of the structure, substrate preferences and localizations of PepT2 in mammals. As PepT2 is expressed in various organs, its functions in the liver, kidney, brain, heart, lung and mammary gland have been addressed. Regulatory factors that affect the expression and function of PepT2, such as transcriptional activation and posttranslational modification, are also discussed (Wang et al. 2022). Lichtinger et al. 2024 established a mechanistic link between proton binding and peptide recognition, revealing key details underpining secondary active transport in POTs.