title: 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.
abstract: 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.
authors.affiliation: Institution of Tumor Immunology, Lund University, Solvegatan 21, s-223 62 Lund, Sweden.
authors.forename: Kajsa M
authors.initials: KM
authors.lastname: Paulsson
authors.forename: Monique J
authors.initials: MJ
authors.lastname: Kleijmeer
authors.forename: Janice
authors.initials: J
authors.lastname: Griffith
authors.forename: Marc
authors.initials: M
authors.lastname: Jevon
authors.forename: Shangwu
authors.initials: S
authors.lastname: Chen
authors.forename: Per O
authors.initials: PO
authors.lastname: Anderson
authors.forename: Hans-Olov
authors.initials: HO
authors.lastname: Sjogren
authors.forename: Suling
authors.initials: S
authors.lastname: Li
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
mesh_terms: 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
chemical_list: D017920:Antiporters; D020755:Coat Protein Complex I; D015395:Histocompatibility Antigens Class I; D007136:Immunoglobulins; D026901:Membrane Transport Proteins; C107762:tapasin