The crystal structure of dipeptidyl peptidase IV (CD26) reveals its functional regulation and enzymatic mechanism

Proc Natl Acad Sci U S A. 2003 Apr 29;100(9):5063-8. doi: 10.1073/pnas.0230620100. Epub 2003 Apr 10.


The membrane-bound glycoprotein dipeptidyl peptidase IV (DP IV, CD26) is a unique multifunctional protein, acting as receptor, binding and proteolytic molecule. We have determined the sequence and 1.8 A crystal structure of native DP IV prepared from porcine kidney. The crystal structure reveals a 2-2-2 symmetric tetrameric assembly which depends on the natively glycosylated beta-propeller blade IV. The crystal structure indicates that tetramerization of DP IV is a key mechanism to regulate its interaction with other components. Each subunit comprises two structural domains, the N-terminal eight-bladed beta-propeller with open Velcro topology and the C-terminal alpha/beta-hydrolase domain. Analogy with the structurally related POP and tricorn protease suggests that substrates access the buried active site through the beta-propeller tunnel while products leave the active site through a separate side exit. A dipeptide mimicking inhibitor complexed to the active site discloses key determinants for substrate recognition, including a Glu-Glu motif that distinguishes DP IV as an aminopeptidase and an oxyanion trap that binds and activates the P(2)-carbonyl oxygen necessary for efficient postproline cleavage. We discuss active and nonactive site-directed inhibition strategies of this pharmaceutical target protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Catalysis
  • Crystallography, X-Ray
  • DNA, Complementary
  • Dipeptidyl Peptidase 4 / chemistry*
  • Dipeptidyl Peptidase 4 / metabolism
  • Molecular Sequence Data
  • Nuclear Magnetic Resonance, Biomolecular
  • Protease Inhibitors / pharmacology
  • Protein Conformation
  • Sequence Homology, Amino Acid
  • Swine


  • DNA, Complementary
  • Protease Inhibitors
  • Dipeptidyl Peptidase 4

Associated data

  • PDB/1ORV
  • PDB/1ORW