Calreticulin binds to the alpha1 domain of MHC class I independently of tapasin.
Prior to binding to antigenic peptide, the major histocompatibility complex (MHC) heavy chain associates with an assembly complex of proteins that includes calreticulin, tapasin, and the transporter associated with antigen processing (TAP). Our data show that calreticulin can bind weakly to Ld without tapasin's assistance, and that deglycosylation of the alpha1 domain results in a primary loss of binding to calreticulin rather than tapasin. We have also shown that high amounts of wild-type tapasin are still unable to associate with MHC class I in the absence of the MHC class I/calreticulin interaction, confirming the central role of calreticulin in the formation of the MHC class I assembly complex.
Turnquist
H R
HR
Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA.
Vargas
S E
SE
McIlhaney
M M
MM
Li
S
S
Wang
P
P
Solheim
J C
JC
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000276:immunology; D017951:Antigen Presentation; D017920:Antiporters / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D037282:Calreticulin; D002478:Cells, Cultured; D015395:Histocompatibility Antigens Class I / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D007136:Immunoglobulins / Q000502:physiology*; D026901:Membrane Transport Proteins; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012261:Ribonucleoproteins / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D000911:Antibodies, Monoclonal; D017920:Antiporters; D002135:Calcium-Binding Proteins; D037282:Calreticulin; D015395:Histocompatibility Antigens Class I; D007136:Immunoglobulins; D026901:Membrane Transport Proteins; D012261:Ribonucleoproteins; C107762:tapasin