Assembly and antigen-presenting function of MHC class I molecules in cells lacking the ER chaperone calreticulin

Immunity. 2002 Jan;16(1):99-109. doi: 10.1016/s1074-7613(01)00260-6.


MHC class I molecules expressed in a calreticulin-deficient cell line (K42) assembled with beta 2-microglobulin (beta2-m) normally, but their subsequent loading with optimal peptides was defective. Suboptimally loaded class I molecules were released into the secretory pathway. This occurred despite the ability of newly synthesized class I to interact with the transporter associated with antigen processing (TAP) loading complex. The efficiency of peptide loading was reduced by 50%-80%, and impaired T cell recognition was observed for three out of four antigens tested. The peptide-loading function was specific to calreticulin, since the defect in K42 could be rectified by transfection with calreticulin but not a soluble form of calnexin, which shares its lectin-like activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigen Presentation*
  • Antiporters / chemistry
  • Biological Transport
  • Calcium-Binding Proteins / physiology*
  • Calreticulin
  • Cells, Cultured
  • Endoplasmic Reticulum / metabolism
  • Heat-Shock Proteins / chemistry
  • Histocompatibility Antigens Class I / analysis
  • Histocompatibility Antigens Class I / chemistry*
  • Histocompatibility Antigens Class I / physiology
  • Immunoglobulins / chemistry
  • Isomerases / chemistry
  • Membrane Transport Proteins
  • Mice
  • Protein Disulfide-Isomerases
  • Ribonucleoproteins / physiology*


  • Antiporters
  • Calcium-Binding Proteins
  • Calreticulin
  • Heat-Shock Proteins
  • Histocompatibility Antigens Class I
  • Immunoglobulins
  • Membrane Transport Proteins
  • Ribonucleoproteins
  • tapasin
  • Isomerases
  • Pdia3 protein, mouse
  • Protein Disulfide-Isomerases