| The novel Bcl 3 interactors Jab 1 , Pirin , Tip 60 and Bard 1 are nuclear proteins which also bind to other transcription factors including c Jun , nuclear factor 1 ( NFI ) , HIV 1 Tat or the tumor suppressor and PolII holoenzyme component Brca 1 , respectively . ^^^ Bcl 3 , p 50 , and either Bard 1 , Tip 60 or Pirin are sequestered into quarternary complexes on NF kappaB DNA binding sites , whereas Jab 1 enhances p 50 Bcl 3 DNA complex formation . ^^^ Furthermore , the histone acetylase Tip 60 enhances Bcl 3 p 50 activated transcription through an NF kappaB binding site , indicating that quarternary complexes containing Bcl 3 interactors modulate NF kappaB driven gene expression . ^^^ These data implicate Bcl 3 as an adaptor between NF kappaB p50 / p52 and other transcription regulators and suggest that its gene activation function may at least in part be due to recruitment of the Tip 60 histone actetylase . . ^^^ |