Avram Hershko

I have been interested in the problem of how proteins are degraded in cells in a selective and regulated fashion. By the use of biochemical approaches, it was found in my laboratory that proteins are marked for degradation by attachment to a small protein, called ubiquitin. We have furthermore discribed several enzymes which catalyze biochemical reactions of the ubiquitin system for protein degradation. The most important of these are ubiquitin-protein ligases, or E3 enzymes, which recognize specific features in certain proteins and target them for degradation at the right time. More recently, I am investigating the roles of several ubiquitin-protein ligases in the control of cell division. Recent work in many laboratories has shown that ubiquitin-mediated protein degradation is involved in many basic biological processes, such as the control of cell proliferation, signal transduction, development, the immune response and the inflammatory response.