Specifically, DPP-4 cleaves the peptide bond between Ala8-Glu9 resulting in the abundant GLP-1 (9–36) amide constituting 60–80 % of total GLP-1 in circulation. DPP-4 is widely expressed in multiple tissues and cell types and exists in both a membrane-anchored and soluble circulating form. Notably, DPP-4 is expressed on the surface of endothelial cells, including those located directly adjacent to GLP-1 secretion sites.
Specifically, DPP-4 cleaves the peptide bond between Ala8-Glu9 resulting in a significant amount of GLP-1 (9–36) amide making up 60–80 % of total GLP-1 in circulation. DPP-4 is broadly distributed across various tissues and cell types and exists in both membrane-bound and soluble circulating forms. Notably, DPP-4 is expressed on the surface of endothelial cells, including those adjacent to sites where GLP-1 is secreted.