Mark W. Hochstrasser

With a focus on ubiquitin and ubiquitin-like proteins, Mark Hochstrasser identified the first physiological substrate of the ubiquitin system. He demonstrated how different ubiquitin-conjugating enzymes collaborate in substrate ubiquitination. In addition, he identified a transmembrane ubiquitin ligase that is central to protein quality control in the endoplasmic reticulum. He developed methods for analyzing how membrane proteins move to the inner nuclear membrane, and identified the proteasome active sites and multiple proteasome assembly chaperones. Hochstrasser also discovered a yeast deubiquitinating enzyme that functions at late endosomes, and his analysis of its human counterpart provided the first evidence linking ubiquitin system defects to cancer.