| 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 . ^^^ |