Aaron Ciechanover. File photo by Bengt Oberger, CC BY-SA 4.0, via Wikimedia Commons.
2004Nobel Prizes
Technion's Aaron Ciechanover and Avram Hershko share the Nobel Prize in Chemistry.
The prize announced on 6 October 2004 honours how cells mark unwanted proteins for destruction, and Irwin Rose is the third laureate.
The story in numbers.
3
laureates share the prize
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27
years from first experiments to the prize
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Here is how it happened.
1977
Hershko and Ciechanover split a cell extract that breaks down proteins.
They study an extract from immature red blood cells that destroys proteins using ATP. It divides into two fractions that do nothing alone and work again when mixed.
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1978
They find a small heat-stable protein and name it APF-1.
Its molecular weight is 9000, and it is the active part of one fraction. It later proves to be ubiquitin.
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1980
APF-1 is shown to attach to the proteins that are to be destroyed.
Two works by Ciechanover, Hershko and Irwin Rose show that many APF-1 molecules bind to the same target protein. Much of the work happens during sabbaticals at the Fox Chase Cancer Center in Philadelphia.
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By 2004
Labelled proteins are sent to the cell's waste disposers.
The proteasomes break down the labelled proteins, and the label is recycled. The process governs cell division, DNA repair, quality control of new proteins and immune defence.
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Avram Hershko, who shared the 2004 prize. File photo by Amos Ben Gershom, CC BY-SA 3.0, via Wikimedia Commons.
6 October 2004
The Royal Swedish Academy of Sciences announces the Nobel Prize in Chemistry.
It goes to Ciechanover, Hershko and Rose for the discovery of ubiquitin-mediated protein degradation. Ciechanover was born in Haifa in 1947 and earned his doctorate at the Technion in 1982.
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1 of 5
Here is why it matters.
Ubiquitin is a small label that tells the cell which proteins to destroy. The Nobel announcement links faults in this system to cervical cancer and cystic fibrosis.
Three more milestones to read next.
Dan Shechtman. File photo by Technion - Israel Institute of Technology, CC BY-SA 3.0, via Wikimedia Commons.
2011
Technion's Dan Shechtman wins the Nobel Prize in Chemistry.
Read the story
Ada Yonath. File photo by Miki Koren, Weizmann Institute of Science, CC BY-SA 3.0, via Wikimedia Commons.
2009
Weizmann Institute's Ada Yonath wins the Nobel Prize in Chemistry.
Read the story
Arieh Warshel in December 2013. File photo by Bengt Nyman, CC BY 2.0, via Wikimedia Commons.
2013
Kibbutz-born Arieh Warshel and Michael Levitt win the Nobel Prize in Chemistry.
Read the story
Where each fact was read.
Sources read on 1 November 2026.