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.
ADA-binding protein; ADABP; ADCP 2; ADCP-2; ADCP2; Adenosine deaminase complexing protein 2; CD 26; CD26; CD26 antigen 3; Dipeptidyl peptidase 4; Dipeptidyl peptidase 4 soluble form; Dipeptidyl peptidase IV; Dipeptidyl peptidase IV membrane form; Dipeptidyl peptidase IV soluble form; Dipeptidylpeptidase 4; Dipeptidylpeptidase IV (CD26, adenosine deaminase complexing protein 2); Dipeptidylpeptidase IV; DPP 4; DPP IV; DPP IV estoenzyme; DPP4; DPP4_HUMAN; DPPIV; Intestinal dipeptidyl peptidase; T cell activation antigen CD26; T-cell activation antigen CD26; TP 103; TP103; cluster of differentiation 26