The binding site of human adenosine deaminase for CD26/Dipeptidyl peptidase IV: the Arg142Gln mutation impairs binding to cd26 but does not cause immune deficiency.

Published

Journal Article

Human, but not murine, adenosine deaminase (ADA) forms a complex with the cell membrane protein CD26/dipeptidyl peptidase IV. CD26-bound ADA has been postulated to regulate extracellular adenosine levels and to modulate the costimulatory function of CD26 on T lymphocytes. Absence of ADA-CD26 binding has been implicated in causing severe combined immunodeficiency due to ADA deficiency. Using human-mouse ADA hybrids and ADA point mutants, we have localized the amino acids critical for CD26 binding to the helical segment 126-143. Arg142 in human ADA and Gln142 in mouse ADA largely determine the capacity to bind CD26. Recombinant human ADA bearing the R142Q mutation had normal catalytic activity per molecule, but markedly impaired binding to a CD26(+) ADA-deficient human T cell line. Reduced CD26 binding was also found with ADA from red cells and T cells of a healthy individual whose only expressed ADA has the R142Q mutation. Conversely, ADA with the E217K active site mutation, the only ADA expressed by a severely immunodeficient patient, showed normal CD26 binding. These findings argue that ADA binding to CD26 is not essential for immune function in humans.

Full Text

Duke Authors

Cited Authors

  • Richard, E; Arredondo-Vega, FX; Santisteban, I; Kelly, SJ; Patel, DD; Hershfield, MS

Published Date

  • November 2000

Published In

Volume / Issue

  • 192 / 9

Start / End Page

  • 1223 - 1236

PubMed ID

  • 11067872

Pubmed Central ID

  • 11067872

Electronic International Standard Serial Number (EISSN)

  • 1540-9538

International Standard Serial Number (ISSN)

  • 0022-1007

Digital Object Identifier (DOI)

  • 10.1084/jem.192.9.1223

Language

  • eng