Aaron Ciechanover
Now if somebody will ask me what ubiquitin is, I say it's a passport…. It's dynamic and it's very flexible.

Nobel Laureate

Aaron Ciechanover

Cancer Biology, Technion - Israel Institute of Technology

Aaron Ciechanover was awarded the 2004 Nobel Prize in Chemistry for characterizing the method that cells use to break down, or degrade, and recycle proteins.


Ciechanover, along with Avram Hershko and Irwin Rose, showed that cells regulate the presence of unwanted proteins by labeling them with the polypeptide ubiquitin — dubbed the “kiss of death” — which results in them being fast tracked for disposal. The discovery is known as the ubiquitin-proteasome system (UPS).

The significance of UPS is far reaching: It is integral to cell division, DNA repair, quality control of newly-produced proteins, and important elements of immune defense; defects with the UPS have been implicated in the development of malignancies and neurodegenerative disorders, including cervical cancer and cystic fibrosis. Knowledge of how protein labeling works means that scientists can target these ailments — and one anti-cancer drug has already come to market as a result of the research.

“Ubiquitin is everywhere, and it's not only for degradation,” Ciechanover said in an interview with Nobelprize.org. “If I would have been asked a few years ago, ‘What's ubiquitin?’ I would have said it's a degradation signal. Now if somebody will ask me what ubiquitin is I say it's a passport…. It's dynamic and it's very flexible. You can use the same molecule to send different signals to different molecules to fulfil different functions.”

Ciechanover is the Distinguished Research Professor at Technion, Israel Institute of Technology in Haifa, and one of Israel’s first Nobel Laureates.