NF-X2 that binds to the DRA X2-box is activator protein 1. Expression cloning of c-Jun.
Human class II MHC Ag are a family of cell surface glycoproteins. Their constitutive expression is limited to B lymphocytes and thymic epithelial cells. In many other cells their expression can be induced by IFN-gamma. Conserved upstream promoter sequences regulate this tissue-specific expression of class II genes. In the DRA promoter, one of these cis-acting regulatory motifs is the X2-box to which nuclear factor X2 (NF-X2) binds. Here, we present the isolation and characterization of the full-length cDNA clone encoding NF-X2. This cDNA clone was isolated by expression cDNA cloning, and encodes the human c-Jun protein, which together with c-Fos forms the heterodimeric activator protein-1 transcription complex. Whereas c-Fos/c-Jun heterodimers do not exist in B cells, they form and bind to the X2-box in class II nonexpressing cells. Thus, c-Fos/c-Jun heterodimers might contribute to the repression of DRA gene expression.
Department of Medicine, Howard Hughes Medical Institute, University of California, San Francisco 94143-0724.
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Andersson
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Peterlin
D001402:B-Lymphocytes / Q000378:metabolism; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D005786:Gene Expression Regulation; D005802:Genes, MHC Class II; D006367:HeLa Cells; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D016755:Proto-Oncogene Proteins c-jun; D012313:RNA / Q000032:analysis; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D012313:RNA