• Issue: Januari 2011
  • Designer: Haimi Kivkovitch
  • Stamp Size: 30 mm x 40 mm
  • Plate no.: 823 (two phosphor bars), 824 (two phosphor bars)
  • Sheet of 15 stamps, Tabs: 5
  • Printers: Joh. Enschede, The Netherlands
  • Method of printing: Offset

Why our proteins must die so that we may live

Proteins are the machines that drive our bodies. They are responsible for all our activities, from the beating of our hearts, to walking, seeing, hearing, digestion, respiration and even the secretion of waste materials. Unlike useful items that surround us, like furniture and clothing, our bodies' proteins are dynamic. They are constantly being destroyed and rebuilt, again and again. Our bodies destroy on a daily basis up to 10% of our proteins and generate new ones instead. This phenomenon raises interesting questions: why does this process occur at all, and how does it occur? Which diseases would happen if this mechanism was to fail? How can we cure such diseases? As part of the body's quality control mechanism, proteins are destroyed after fulfilling their specific function in case they have been damaged by heat, by pollutants, by genetic mutation, or simply because they are no longer needed.

Professors Aaron Ciechanover and Avram Hershko of the Technion - Israel Institute of Technology, and Irwin Rose of the University of California, Irvine, USA, were jointly awarded the 2004 Nobel Prize in Chemistry for discovering the mechanism that removes damaged or unnecessary proteins. These proteins are labeled for destruction by another small protein called ubiquitin, whose general structure is shown on the stamp. The structure was adopted from W. J. Cook and his coworkers, the Journal of Molecular Biology, 1987. Once tagged by this "kiss of death" the labeled proteins are removed by a biological shredding machine called the proteasome, while sparing healthy, untagged proteins. Aberrations in this protein destruction process may result in numerous sicknesses, including certain types of cancers and brain diseases. Many pharmaceutical companies are working to develop drugs to combat such diseases. One such drug to treat multiple myeloma, which is a form of blood cancer, is already used clinically.

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Ribosome translates DNA code into life

Ribosome is the biological machine in every living cell that makes proteins from amino acids. Genetic information, which is stored in our DNA, is copied into RNA, which is then read by the ribosome and used to create proteins. This process is known as translation, meaning that the ribosome translates the genetic information from RNA into proteins, which in turn control the structure and function of all living organisms. The ribosome is a huge machine, consisting of three RNA chains and more than 50 different proteins. Understanding the ribosomal structure and its operating mechanism is critical for the scientific understanding of all kinds of life. In particular, this insight into the life of pathogenic bacteria opened the door to the use of ribosomes as an important target for new antibiotics. Many of today's antibiotics cure various diseases by blocking the function of bacterial ribosomes.

The 2009 Nobel Prize in Chemistry was awarded jointly to professors Ada E. Yonath of the Weizmann Institute of Science, Venkatraman Ramakrishnan of the Medical Research Council, Cambridge, UK, and Thomas A. Steitz of Yale University, USA. They showed what the ribosome looks like and how it functions at the atomic level. All three used a method called X-ray crystallography to map the position for each and every one of the hundreds of thousands of atoms that make up the ribosome. The image on the stamp, which is adopted from a paper published by Ada Yonath and her coworkers in 2001 in Nature magazine, shows a view into the tunnel of the large ribosomal subunit from which the newly constructed chain of amino acids exits. This huge structure shows the ribosomal proteins (shown in orange), the ribosomal RNA (blue and pink) together with the antibiotic erythromycin (red).

Ehud Keinan
Professor of Chemistry
Technion - Israel Institute of Technology
President of the Israel Chemical Society
Editor in Chief, Israel Journal of Chemistry
Chairman of the Chemistry Committee
Ministry of Education

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International Year of Chemistry 2011