v-rel- and c-rel-protein complexes bind to the NF-kappa B site in vitro

Previous work by others has revealed homology between the rel oncogene and the transcription factor NF-kappa B. Further, in vitro-translated v-rel protein and c-rel protein are able to bind to an oligonucleotide containing the kappa B binding site. Unlike the in vitro-translated product, cellular Rel protein exists in high molecular weight complexes with several other proteins. In this report we show that immunopurified cellular complexes containing the v-rel protein and/or the c-rel protein are also able to bind to an oligonucleotide containing the kappa B site. These cellular complexes are heterogeneous in size, and all sizes appeared to have binding activity. UV cross-linking demonstrated that the Rel proteins themselves were bound to the DNA. Thus it is likely that the Rel proteins play a direct role in transcriptional regulation.