Ubiquitin's duality
Ubiquitin's duality
Ubiquitin does more than mark proteins for degradation. In 2004, Ingrid Wertz, a University of California, Davis graduate student, and advisor Vishva Dixit of Genentech, demonstrated that the protein A20, which was known to downregulate tumor necrosis factor á (TNFá) signaling, has both an ubiquitin ligase domain and a deubiquitinating domain.1 Wertz, now at the University of Washington, St. Louis, says she found the presence of these opposing functions disconcerting: "I was thinking, h