DPP-4
Also: dipeptidyl peptidase-4, dipeptidyl peptidase IV, DPP4, CD26
DPP-4 (dipeptidyl peptidase-4), also called CD26, is an enzyme that removes two amino acids from certain peptides, including the incretin hormones GLP-1 and GIP.
What Does DPP-4 Stand For?
DPP-4 stands for dipeptidyl peptidase-4. DPP4 names the gene that encodes this protein, and CD26 is another name for the same protein, particularly in immune-cell research. The gene, protein, and a medicine targeting the protein are different things. [1]
DPP-4 is a serine protease: an enzyme that cuts peptide bonds using a serine residue at its active site. It exists on cell surfaces and in a soluble circulating form. Its activity removes a pair of amino acids from the amino-terminal end of suitable peptide substrates, commonly when the second residue is proline or alanine. [1, 2]
Why DPP-4 Matters for GLP-1 and GIP
GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) are incretin hormones released in response to food. They contribute to glucose-dependent insulin secretion. DPP-4 cleavage rapidly reduces the activity of their native forms. [2, 3]
Early experiments identified a truncated GLP-1 metabolite in human plasma and investigated DPP-4's role in its formation. That finding helps explain why measuring total hormone material is not equivalent to measuring intact, active hormone. An assay may detect a breakdown product that no longer has the original receptor activity. [2]
This distinction also explains why peptide research considers both half-life and susceptibility to proteases. A molecule's sequence and chemical modifications affect how quickly enzymes can break it down.
DPP-4 Inhibitors and GLP-1 Receptor Agonists
DPP-4 inhibitors, often called gliptins, target the enzyme. Sitagliptin is an example: its label describes preservation of active GLP-1 and GIP, with resulting effects on glucose-dependent insulin secretion and glucagon. [3]
Semaglutide takes a different approach. It directly activates GLP-1 receptors and contains modifications that protect it from rapid DPP-4 degradation. It does not work by inhibiting the enzyme. [4]
| Approach | Main target | Relationship to native incretins |
|---|---|---|
| DPP-4 inhibitor | DPP-4 enzyme | Slows their enzymatic inactivation |
| GLP-1 receptor agonist | GLP-1 receptor | Provides receptor stimulation using an engineered molecule |
These mechanisms do not make the two drug classes interchangeable. Prescribing decisions require a product's evidence, approved indications, and individual clinical assessment.
What Researchers Should Distinguish
Protein abundance, enzyme activity, and clinical outcomes are separate measurements. Detecting more DPP4 protein does not by itself demonstrate increased cleavage of a particular hormone or establish a treatment effect.
When reading a study, identify whether it measured gene expression, protein concentration, catalytic activity, or intact hormone levels. Also distinguish cell experiments from human evidence. Our GLP-1 research overview connects these mechanisms to clinical studies.