The DNA-binding ability of HIVEP3/KRC decreases upon activation of V(D)J recombination.
Somatic V(D)J recombination of the immune receptor genes is mediated by the recombination signal sequence (RSS) and the recombination-activating genes RAG1 and RAG2. Previously, proteins binding specifically to the RSS have been characterized in nuclear extracts of T and B lymphocytes. Further elucidation of the role of those RSS-binding proteins in V(D)J recombination, however, has been hampered by the fact that their identities have not been established. Here, we show that the major RSS-binding protein present in the nuclear extracts of B lymphocytes is an Mr 135,000 species. Notably, its affinity for the RSS decreased when RAG1 and RAG2 were induced. In immunoblot analyses and gel supershift assays, we showed that KRC antisera react with the Mr 135,000 RSS-binding protein. We previously cloned KRC from a thymocyte expression library using 32P-RSS as a ligand and showed that KRC fusion proteins bind specifically to the RSS and to the kappaB enhancer motif. The lymphoid expression and DNA-binding characteristics suggest that KRC may be involved in lymphocyte development.
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Room S2077, Davis Medical Center, Department of Internal Medicine, The Ohio State University, 480 West 9th Avenue, Columbus, OH 43210, USA. wu.39@osu.edu
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D000918:Antibody Specificity; D001402:B-Lymphocytes / Q000276:immunology*; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D006801:Humans; D016328:NF-kappa B / Q000235:genetics; D011485:Protein Binding; D011947:Receptors, Antigen, B-Cell / Q000235:genetics*; D011995:Recombination, Genetic; D020298:U937 Cells
D004268:DNA-Binding Proteins; C425103:HIVEP3 protein, human; D016328:NF-kappa B; D011947:Receptors, Antigen, B-Cell