of their study they were able to observe the mechanism by which interconversion of the two forms of phosphorylase takes place: reversible protein phosphorylation. Explained simply, in reversible protein phosphorylation a protein kinase takes a phosphate group from adenosine triphosphate (ATP) and attaches it to a specific site on a protein, introducing both extra mass and negative charge at that site. This can alter the protein's shape and turn its function in a biological process up or down, either by changing its activity or its ability to bind to another protein. The protein can be converted back to its original state by a protein phosphatase that removes the phosphate. This cycle controls numerous metabolic processes, and plays a central role in the regulation of cell division, shape, and motility. Derangement of specific protein phosphorylation pathways is important in human disease, including cancer and diabetes. Fischer and Krebs were awarded the Nobel Prize for Physiology or Medicine in 1992 for the discovery of reversible protein phosphorylation, . Later life and death Krebs's interest in teaching and administration led him to leave the University of Washington to become the founding chairman of the Department of Biochemistry at the University of California, Davis. In 1977 he returned to the University of Washington as Chairman of the Department of Pharmacology. Krebs was hearing impaired. Krebs died on December 21, 2009. His wife, Virginia, died in 2018. He is survived by three children. References and notes Bibliography External links Hughes, R. 1998. After the Prize The Official Site of Louisa Gross Horwitz Prize University of Washington Columns Magazine Obituary Edmond H. Fischer, "Edwin G. Krebs", Biographical Memoirs of the National Academy of Sciences (2010) 1918 births 2009 deaths American biochemists Washington University School of Medicine alumni Nobel laureates affiliated with Missouri University of Washington faculty Nobel laureates in Physiology or Medicine American Nobel laureates People from Urbana, Illinois People from Bond County, Illinois University of Illinois Urbana-Champaign alumni Members of the United States National Academy of Sciences American Presbyterians American people of German descent Howard Hughes Medical Investigators People from Allamakee County, Iowa Recipients of the Albert Lasker Award for Basic Medical Research Washington University in St. Louis alumni University of California, Davis faculty