EBNA-2 AND EBNA-3C EXTENSIVELY AND MUTUALLY EXCLUSIVELY ASSOCIATE WITH RBPJ-KAPPA IN EPSTEIN-BARR VIRUS-TRANSFORMED B-LYMPHOCYTES

Although genetic and biochemical data indicate that the cell protein R BPJ kappa is a mediator of EBNA-2 and EBNA-3C effects on transcription al regulatory elements, the extent of association of these Epstein-Bar r virus nuclear proteins with RBPJ kappa in transformed B lymphocytes has not been determined. We now report that most of the EBNA-2 and at least 20% of the EBNA-3C coimmunoprecipitated with RBPJ kappa from ext racts of transformed B lymphocytes that contained most of the cellular EBNA-2 and EBNA3C. Both proteins are associated preferentially with t he smaller of the two RBPJ kappa isoforms. EBNA-2-RBPJ kappa complexes do not contain EBNA-3C, and EBNA-3C-RBPJ kappa complexes do not conta in EBNA-2. Although EBNA-2 and EBNA-3C are extensively associated with RBPJ kappa, a fraction of RBPJ kappa appears to be free of EBNAs afte r repeated immunoprecipitations with anti-EBNA, Epstein-Barr virus-imm une, human antibody. Promoters with RBPJ kappa sites in their regulato ry elements are likely to be differentially regulated by these RBPJ ka ppa-EBNA-2 and RBPJ kappa-EBNA-3 complexes.