Accuracy is a remarkable feature of a large number of biological processes. To maintain homeostasis, cellular protein degradation must be carried out with no less efficiency or precision than transcription and translation. My lab is trying to understand how the cell achieves accurate control of protein degradation and how its failure may lead to neurodegeneration and aging. Using modern enzymological techniques, namely single-molecule fluorescence/force spectroscopy and cryo-electron microscopy, we are investigating how the information in ubiquitin configurations is decoded by the proteasome, a universal protein machine in eukaryotic species, to command an accurate rate of protein degradation.