Combined immunodeficiency due to a mutation in the γ1 subunit of the coat protein I complex

J Clin Invest. 2021 Feb 1;131(3):e140494. doi: 10.1172/JCI140494.


The coat protein I (COPI) complex mediates retrograde trafficking from the Golgi to the endoplasmic reticulum (ER). Five siblings with persistent bacterial and viral infections and defective humoral and cellular immunity had a homozygous p.K652E mutation in the γ1 subunit of COPI (γ1-COP). The mutation disrupts COPI binding to the KDEL receptor and impairs the retrieval of KDEL-bearing chaperones from the Golgi to the ER. Homozygous Copg1K652E mice had increased ER stress in activated T and B cells, poor antibody responses, and normal numbers of T cells that proliferated normally, but underwent increased apoptosis upon activation. Exposure of the mutants to pet store mice caused weight loss, lymphopenia, and defective T cell proliferation that recapitulated the findings in the patients. The ER stress-relieving agent tauroursodeoxycholic acid corrected the immune defects of the mutants and reversed the phenotype they acquired following exposure to pet store mice. This study establishes the role of γ1-COP in the ER retrieval of KDEL-bearing chaperones and thereby the importance of ER homeostasis in adaptive immunity.

Keywords: Adaptive immunity; Immunology.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Substitution
  • Animals
  • Apoptosis / genetics
  • Apoptosis / immunology*
  • B-Lymphocytes / immunology*
  • Coatomer Protein / genetics
  • Endoplasmic Reticulum / genetics
  • Endoplasmic Reticulum / immunology
  • Endoplasmic Reticulum Stress / genetics
  • Endoplasmic Reticulum Stress / immunology*
  • Golgi Apparatus / genetics
  • Golgi Apparatus / immunology
  • Humans
  • Lymphocyte Activation*
  • Mice
  • Mice, Mutant Strains
  • Mutation, Missense*
  • Receptors, Peptide / genetics
  • Receptors, Peptide / immunology
  • Severe Combined Immunodeficiency / genetics
  • Severe Combined Immunodeficiency / immunology*
  • T-Lymphocytes / immunology*


  • COPG1 protein, human
  • Coatomer Protein
  • KDEL receptor
  • Receptors, Peptide