hUBC9 associates with MEKK1 and type I TNF-α receptor and stimulates NFκB activity

hUBC9, an E2 ubiquitin conjugating enzyme, was identified by yeast two-hybrid screening and coprecipitation studies to interact with MEKK1 and the type I TNF-alpha receptor, respectively. Because both of these proteins regulate NF kappa B activity, the role of hUBC9 in modulating NF kappa B activity was investigated. Overexpression of hUBC9 in HeLa cells stimulated the activity of NF kappa B as determined by NF kappa B reporter and IL-6 secretion assays, hUBC9 also synergized with MEKK1 to activate NF kappa B reporter activity. Thus, hUBC9 modulates NF kappa B activity which, at least in part, can be attributed to its interaction with MEKK1 and the type I TNF-alpha receptor. (C) 1998 Federation of European Biochemical Societies.