From Proteopediaproteopedia link
Human dipeptidyl peptidase IV/CD26 in complex with an inhibitor
[DPP4_HUMAN] Cell surface glycoprotein receptor involved in the costimulatory signal essential for T-cell receptor (TCR)-mediated T-cell activation. Acts as a positive regulator of T-cell coactivation, by binding at least ADA, CAV1, IGF2R, and PTPRC. Its binding to CAV1 and CARD11 induces T-cell proliferation and NF-kappa-B activation in a T-cell receptor/CD3-dependent manner. Its interaction with ADA also regulates lymphocyte-epithelial cell adhesion. In association with FAP is involved in the pericellular proteolysis of the extracellular matrix (ECM), the migration and invasion of endothelial cells into the ECM. May be involved in the promotion of lymphatic endothelial cells adhesion, migration and tube formation. When overexpressed, enhanced cell proliferation, a process inhibited by GPC3. Acts also as a serine exopeptidase with a dipeptidyl peptidase activity that regulates various physiological processes by cleaving peptides in the circulation, including many chemokines, mitogenic growth factors, neuropeptides and peptide hormones. Removes N-terminal dipeptides sequentially from polypeptides having unsubstituted N-termini provided that the penultimate residue is proline.        
Publication Abstract from PubMed
A series of beta-substituted biarylphenylalanine amides were synthesized and evaluated as inhibitors of dipeptidyl peptidase IV (DPP-4) for the treatment of type 2 diabetes. Optimization of the metabolic profile of early analogues led to the discovery of (2S,3S)-3-amino-4-(3,3-difluoropyrrolidin-1-yl)-N,N-dimethyl-4-oxo-2-(4-[1 ,2,4]triazolo[1,5-a]pyridin-6-ylphenyl)butanamide (6), a potent, orally active DPP-4 inhibitor (IC(50) = 6.3 nM) with excellent selectivity, oral bioavailability in preclinical species, and in vivo efficacy in animal models. Compound 6 was selected for further characterization as a potential new treatment for type 2 diabetes.
(2S,3S)-3-Amino-4-(3,3-difluoropyrrolidin-1-yl)-N,N-dimethyl-4-oxo-2-(4-[1 ,2,4]triazolo[1,5-a]-pyridin-6-ylphenyl)butanamide: a selective alpha-amino amide dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes.,Edmondson SD, Mastracchio A, Mathvink RJ, He J, Harper B, Park YJ, Beconi M, Di Salvo J, Eiermann GJ, He H, Leiting B, Leone JF, Levorse DA, Lyons K, Patel RA, Patel SB, Petrov A, Scapin G, Shang J, Roy RS, Smith A, Wu JK, Xu S, Zhu B, Thornberry NA, Weber AE J Med Chem. 2006 Jun 15;49(12):3614-27. PMID:16759103
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.