Human Dipeptidyl Peptidase 4 / CD26 (DPP4) Enzyme

Background

Dipeptidyl peptidase 4 (DPP4), also known as CD26, is a transmembrane glycoprotein and serine protease that plays a significant role in regulating glucose metabolism, immune function, and cell signaling. It is expressed on the surface of various cell types, including epithelial cells, endothelial cells, and immune cells such as T cells and B cells. DPP4 is widely known for its role in glucose homeostasis through its enzymatic activity, where it deactivates incretin hormones like glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). These hormones promote insulin release in response to meals, and their inactivation by DPP4 reduces insulin secretion, thereby impacting blood sugar levels. Beyond its metabolic functions, DPP4 also participates in various immune regulatory pathways. As CD26, it is involved in T-cell activation and co-stimulation. DPP4 is linked to inflammatory processes and certain cancers, particularly due to its enzymatic activity and role in regulating immune responses. Additionally, the soluble form of DPP4 (sDPP4), which circulates in the plasma, plays a role in systemic metabolic and immune regulation.