- The infected cell protein 0 of herpes simplex virus 1 dynamically interacts with proteasomes, binds and activates the cdc34 E2 ubiquitin-conjugating enzyme, and possesses in vitro E3 ubiquitin ligase activity. Van Sant, C., Hagglund, R., Lopez, P., Roizman, B. Proc. Natl. Acad. Sci. U.S.A. (2001)