Telomerase earned Elizabeth Blackburn, Carol Greider, and Jack Szostak the 2009 Nobel Prize in Physiology or Medicine.
The scientists were recognized for discovering how chromosomes are protected by telomeres and the enzyme telomerase. Telomeres are repetitive DNA-protein structures at chromosome ends. They help prevent chromosome ends from being mistaken for broken DNA and protect chromosome stability.
Carol Greider and Elizabeth Blackburn identified telomerase in 1984. The enzyme adds telomeric DNA repeats, compensating for the difficulty of fully copying the ends of linear chromosomes. Jack Szostak’s work helped demonstrate the protective role of telomeres.
Telomerase activity is high in many stem cells and most cancer cells, but low in most ordinary adult cells. This does not mean telomerase alone explains aging or cancer. A common mistake is to call telomeres enzymes: telomeres are chromosome-end structures, while telomerase is the enzyme that maintains them.