The 2004 Nobel Prize for Chemistry has gone to three scientists for their studies of what might be called the "garbage cleaners" of biological cells.
Ciechanover (l) and Hershko (r) were the centre of attention on Wednesday
Aaron Ciechanover and Avram Hershko from Israel and Irwin Rose from the US revealed a key process involved in ridding cells of redundant proteins.
They showed how these molecules, which build and maintain our bodies, can be tagged to identify them for destruction.
Researchers are now trying to use this knowledge to produce new types of drugs.
Ciechanover, 57, Hershko, 67, and Rose, 78, each receive a medal and share of the $1.3m prize.
The Nobel Prizes are named after Alfred Nobel, the wealthy Swedish industrialist and inventor of dynamite.
Earlier this week, researchers in medicine were honoured for their breakthrough studies on the human sense of smell, and physicists were given a Nobel for their pioneering work on the fundamentals of matter.
At a time when the human genome is very much in the spotlight, commentators say the 2004 chemistry Nobel Prize is a useful reminder that genes are only the start of the process of life.
Genes carry the code for the design of proteins, the molecular machines that sustain all living things. And just like machines in the home or in the factory, proteins get damaged as they do their jobs.
If the defective ones are not cleaned away, cells soon stop functioning properly.
Ciechanover, Hershko and Rose discovered that a molecule called ubiquitin is the key to this garbage collection process. It attaches itself to damaged proteins, labelling them ready for destruction.
Some have described this process as a cellular "kiss of death".
Once marked, the redundant proteins are moved away to the cell's equivalent of a scrapheap, called the proteasome, where they are dismembered, and their parts made ready for disposal.
Ubiquitin is also involved in repairing faulty DNA and quality control of newly made proteins.
Diseases caused by the failure of the clean-up mechanism include cervical cancer and cystic fibrosis. The Royal Swedish Academy of Sciences in its citation said an understanding of ubiquitin would lead to new kinds of drugs.
Scientists are trying to hijack the process, either to prevent the breakdown of proteins or to make the cell destroy disease-causing ones.
Ciechanover and Hershko are both at Technion (Israel Institute of Technology), Haifa. Rose is at the University of California, Irvine.