The N-terminal region of tapasin is required to stabilize the MHC class I loading complex

Eur J Immunol. 1999 Jun;29(6):1858-70. doi: 10.1002/(SICI)1521-4141(199906)29:06<1858::AID-IMMU1858>3.0.CO;2-C.

Abstract

Tapasin mediates the binding of MHC class I molecules to the transporter associated with antigen processing (TAP). Deletion mutants of tapasin were used to examine the effect of tapasin on interactions within the MHC class I complex. Binding to TAP is mediated by the C-terminal region of tapasin. Michaelis-Menten analysis of peptide transport shows that this interaction is sufficient to increase TAP levels without significantly affecting the intrinsic translocation rate. Weak interactions exist between MHC class I molecules and TAP in the absence of tapasin, and between free heavy chains and TAP-tapasin complexes in the absence of beta2-microglobulin. The N-terminal 50 residues of tapasin constitute the key element which converts the sum of these weak interactions into a stable complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 2
  • ATP-Binding Cassette Transporters / metabolism
  • Antigen Presentation
  • Antiporters / chemistry*
  • Antiporters / genetics
  • Antiporters / metabolism*
  • Base Sequence
  • Binding Sites / genetics
  • Biological Transport, Active
  • Calcium-Binding Proteins / metabolism
  • Calreticulin
  • Cell Line
  • DNA Primers / genetics
  • Drug Stability
  • Heat-Shock Proteins / metabolism
  • Histocompatibility Antigens Class I / metabolism*
  • Humans
  • Immunoglobulins / chemistry*
  • Immunoglobulins / genetics
  • Immunoglobulins / metabolism*
  • Isomerases / metabolism
  • Kinetics
  • Macromolecular Substances
  • Membrane Transport Proteins
  • Molecular Chaperones / metabolism
  • Protein Binding
  • Protein Disulfide-Isomerases
  • Ribonucleoproteins / metabolism
  • beta 2-Microglobulin / metabolism

Substances

  • ATP Binding Cassette Transporter, Subfamily B, Member 2
  • ATP-Binding Cassette Transporters
  • Antiporters
  • Calcium-Binding Proteins
  • Calreticulin
  • DNA Primers
  • Heat-Shock Proteins
  • Histocompatibility Antigens Class I
  • Immunoglobulins
  • Macromolecular Substances
  • Membrane Transport Proteins
  • Molecular Chaperones
  • Ribonucleoproteins
  • TAP1 protein, human
  • beta 2-Microglobulin
  • tapasin
  • Isomerases
  • Protein Disulfide-Isomerases
  • PDIA3 protein, human