The tetraspanin protein CD82 associates with both free HLA class I heavy chain and heterodimeric beta 2-microglobulin complexes.
CD82 is a tetraspan transmembrane protein on NK/LAK-susceptible targets. A single highly glycosylated protein of heterogeneous molecular mass (50-90 kDa) was immunoprecipitated by anti-CD82 from Nonidet P-40 lysates of various B cell lines, Raji, Daudi, 721, and 721.134. Using the milder detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), additional proteins were coprecipitated with CD82 from surface iodinated B cell lines, including a major band at 45 kDa, identified as the HLA class I heavy chain by sequential immunoprecipitations and sequential immunoprecipitation-Western blot analysis. Cocapping experiments confirmed the molecular association of CD82 and HLA class I at the cell surface of these B cell lines. CD82 could be coprecipitated with both mature and beta 2-microglobulin (beta 2m)-free heavy chains of MHC-I from CHAPS extracts. No association between MHC-I and CD82 was found in the beta 2m-deficient Daudi cell line or after co-in vitro translation of CD82, MHC heavy chain, and beta 2m mRNA. The most likely source of free class I heavy chains at the cell surface is by dissociation of beta 2m-associated class I molecules. These results suggest that association of CD82-MHC-I takes place at the cell surface and could interfere with the capacity of the MHC-I complex to protect targets from NK-mediated cytotoxicity.
Lagaudrière-Gesbert
C
C
Immunomodulation and Autoimmunity Laboratory, National Institute of Health and Medical Research, Paris, France.
Lebel-Binay
S
S
Wiertz
E
E
Ploegh
H L
HL
Fradelizi
D
D
Conjeaud
H
H
D015703:Antigens, CD; D001402:B-Lymphocytes / Q000378:metabolism; D002236:Carbohydrate Conformation; D002460:Cell Line; D006680:HLA Antigens / Q000378:metabolism*; D015395:Histocompatibility Antigens Class I / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D051861:Kangai-1 Protein; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D011940:Receptor Aggregation; D001613:beta 2-Microglobulin / Q000737:chemistry / Q000378:metabolism*
D015703:Antigens, CD; C497688:CD82 protein, human; D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D051861:Kangai-1 Protein; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011134:Polysaccharides; D011518:Proto-Oncogene Proteins; D001613:beta 2-Microglobulin