Association of tapasin and COPI provides a mechanism for the retrograde transport of major histocompatibility complex (MHC) class I molecules from the Golgi complex to the endoplasmic reticulum.
Tapasin is a subunit of the transporter associated with antigen processing (TAP). It associates with the major histocompatibility complex (MHC) class I. We show that tapasin interacts with beta- and gamma-subunits of COPI coatomer. COPI retrieves membrane proteins from the Golgi network back to the endoplasmic reticulum (ER). The COPI subunit-associated tapasin also interacts with MHC class I molecules suggesting that tapasin acts as the cargo receptor for packing MHC class I molecules as cargo proteins into COPI-coated vesicles. In tapasin mutant cells, neither TAP nor MHC class I are detected in association with the COPI coatomer. Interestingly, tapasin-associated MHC class I molecules are antigenic peptide-receptive and detected in both the ER and the Golgi. Our data suggest that tapasin is required for the COPI vesicle-mediated retrograde transport of immature MHC class I molecules from the Golgi network to the ER.
Paulsson
Kajsa M
KM
Institution of Tumor Immunology, Lund University, Solvegatan 21, s-223 62 Lund, Sweden.
Kleijmeer
Monique J
MJ
Griffith
Janice
J
Jevon
Marc
M
Chen
Shangwu
S
Anderson
Per O
PO
Sjogren
Hans-Olov
HO
Li
Suling
S
Wang
Ping
P
D017920:Antiporters / Q000378:metabolism*; D001692:Biological Transport; D002460:Cell Line; D020755:Coat Protein Complex I / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D007136:Immunoglobulins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D013347:Subcellular Fractions / Q000378:metabolism
D017920:Antiporters; D020755:Coat Protein Complex I; D015395:Histocompatibility Antigens Class I; D007136:Immunoglobulins; D026901:Membrane Transport Proteins; C107762:tapasin