Massachusetts General Hospital (MGH) investigators have discovered the mechanism by which cells sense dysfunction of the proteasome—a cellular component that degrades unneeded or defective proteins—and respond in a previously undescribed manner, by editing the amino acid sequence of a key sensing protein. Proteasome dysfunction can lead to the type of buildup of aberrant proteins that characterizes neurodegenerative disorders such as Alzheimer’s disease and is also seen in normal aging. The report is being published in the journal Cell.