ISOLATION OF A REL-RELATED HUMAN CDNA THAT POTENTIALLY ENCODES THE 65-KD SUBUNIT OF NF-KAPPA-B

A DNA probe that spanned a domain conserved among the proto-oncogene c-rel, the Drosophila morphogen dorsal, and the p50 DNA binding subunit of NF-KB was generated from Jurkat T cell complementary DNA with the polymerase chain reaction (PCR) and degenerate oligonucleotides. This probe was used to identify a rel-related complementary DNA that hybridized to a 2.6-kilobase messenger RNA present in human T and B lymphocytes. In vitro transcription and translation of the complementary DNA resulted in the synthesis of a protein with an apparent molecular size of 65 kilodaltons (kD). The translated protein showed weak DNA binding with a specificity for the KB binding motif. This protein-DNA complex comigrated with the complex obtained with the purified human p65 NF-KB subunit and binding was inhibited by IKB-alpha and -beta-proteins. In addition, the 65-kD protein associated with the p50 subunit of NF-KB and the KB probe to form a complex with the same electrophoretic mobility as the NF-KB-DNA complex. Therefore the rel-related 65-kD protein may represent the p65 subunit of the active NF-KB transcription factor complex.