Robert Cohen Professor

Office: Mrb 273

Phone: (970) 492-4117



  • Ph.D., University of California at Berkeley


Molecular recognition and protein-protein interactions as applied to ubiquitin biochemistry and ubiquitin-proteasome mediated protein degradation. The ubiquitin system is the major route of regulated intracellular proteolysis in all eukaryotes, and it is responsible for the control of numerous key regulatory proteins. In this pathway, proteins are modified by covalent attachment of ubiquitin, a 76-amino acid protein. Typically, multiple ubiquitins in the form of a polyubiquitin chain are elaborated from one or more lysine sidechains of the target protein. Classically, polyubiquitinated proteins are known to be recognized and degraded by the 26S proteasome, a 2.5 MDa ATP-dependent protease complex. However, depending upon the types of ubiquitin-ubiquitin linkages in the polyubiquitin chain, ubiquitination also can lead to other fates. Thus, mono- or polyubiquitin signals are used in endocytosis and protein trafficking, transcription activation, kinase activation cascades, and chromatin remodeling. Ubiquitin can be removed from conjugates through the action of various deubiquitinating enzymes (DUBs); consequently, many DUBs serve important regulatory functions. Our research is focused on three areas of ubiquitin biochemistry: (1) recognition of linkage-specific polyubiquitin conjugates, (2) the structures, mechanisms, and functions of deubiquitinating enzymes, and (3) quantitation of  ubiquitin homeostasis and dynamics in living cells. Our experimental approaches range from protein biochemistry and biophysical studies to cell biology.


High-affinity free ubiquitin sensors for quantifying ubiquitin homeostasis and deubiquitinationYun-Seok Choi, Sarah A. Bollinger, Luisa F. Prada, Francesco Scavone, Tingting Yao & Robert E. CohenNature Methods 16: 771–777, 2019
Structural basis for the activation and inhibition of the UCH37 deubiquitylaseRyan T VanderLinden, Casey W Hemmis, Benjamin Schmitt, Ada Ndoja, Frank G Whitby, Howard Robinson, Robert E Cohen, Tingting Yao*, Christopher P Hill*Molecular Cell 57: 901-911, 2015
Mixed-linkage ubiquitin chains send mixed messagesMark A.Nakasone, NuritLivnat-Levanon, Michael H.Glickman, Robert E.Cohen, DavidFushmanStructure 21: 727-740, 2013
Polyubiquitin-sensor proteins reveal localization and linkage-type dependence of cellular ubiquitin signalingJoshua J Sims, Francesco Scavone, Eric M Cooper, Lesley A Kane, Richard J Youle, Jef D Boeke & Robert E CohenNature Methods 9: 303–309, 2009
Linkage-Specific Avidity Defines the Lysine 63-Linked Polyubiquitin-Binding Preference of Rap80Joshua J. Sims & Robert E. CohenMolecular Cell 33: 775-783, 2009
Avid interactions underlie the Lys63-linked polyubiquitin binding specificities observed for UBA domainsJoshua J Sims, Aydin Haririnia, Bryan C Dickinson, David Fushman & Robert E CohenNature Structural & Molecular Biology 16: 883–889, 2009
Specificity of the BRISC Deubiquitinating Enzyme Is Not Due to Selective Binding to Lys63-linked PolyubiquitinEric M. Cooper, Jef D. Boeke and Robert E. CohenJ Biol Chem. 285: 10344-10352, 2010
K63?specific deubiquitination by two JAMM/MPN+ complexes: BRISC?associated Brcc36 and proteasomal Poh1Eric M Cooper, Colleen Cutcliffe, Troels Z Kristiansen, Akhilesh Pandey, Cecile M Pickart & Robert E CohenEMBO J 28: 621-631, 2009
Evidence for bidentate substrate binding as the basis for the K48 linkage specificity of otubain 1Tao Wang, Luming Yin, Eric M. Cooper, Ming-Yih Lai, Seth Dickey, Cecile M. Pickart, David Fushman, Keith D. Wilkinson, Robert E. Cohen & Cynthia WolbergerJ Mol Biol. 386: 1011-1023, 2009