CD26; dipeptidyl peptidase 4; dipeptidyl peptidase IV; DPP IV; T-cell activation antigen CD26; TP103; adenosine deaminase (ADA) complexing protein 2; ADABP (DPP4, ADCP2)

Introduction

Identical to dipeptidyl peptidase IV (DPPIV) & ADA-complexing protein-2.

Function

• metabolizes incretins
• binds extracellular adenosine deaminase
• cofactor with CD4 for HIV entry into cells
• removes N-terminal dipeptides sequentially from polypeptides having unsubstituted N-termini provided that the penultimate residue is proline
• role in T-cell activation
• release of an N-terminal dipeptide, Xaa-Yaa-|-Zaa-, from a polypeptide, preferentially when Yaa is Pro, provided Zaa is neither Pro nor hydroxyproline

Structure

• homodimer or heterodimer with seprase (FAP)
• belongs to the peptidase S9B family, DPPIV subfamily

Compartment

• cell membrane
• dipeptidyl peptidase 4 soluble form: secreted
  • derives from the membrane form by proteolytic processing

Expression

• activated T cells & B cells
• NK cells
• macrophages
• renal proximal tubular epithelial cells
• small intestinal epithelium
  • expressed in poorly differentiated crypt cells of small intestine as well as in mature villous cells
• expressed at very low levels in the colon
• biliary canaliculae
• splenic sinus lining cells

Pathology

• peripheral blood T cells of patients with mycosis fungoides stain weakly to negative with antibody

Pharmacology

• inhibitors of DPP4 (gliptins) are used for treatment of type 2 diabetes

More general terms

• CD antigen
• plasma membrane protein
• dipeptidyl peptidase (DPP)

Additional terms

• adenosine deaminase (adenosine aminohydrolase, ADA)
• gliptin; dipeptidyl peptidase-4 inhibitor; DPP-4 inhibitor
• T lymphocyte (T-cell, thymocyte)

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:1803
• OMIM: https://mirror.omim.org/entry/102720
• UniProt: http://www.uniprot.org/uniprot/P27487.html
• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=1803