Extended Data Figure 1. Primary covalent ligand screen against OTUB1.

(a) Analysis of aggregate chemoproteomic data for DUBs. Top 10 candidate DUBs described in Figure 1c for total aggregate spectral counts of the particular probe-modified cysteine found in our aggregate chemoproteomic data showing OTUB1 C23 appears far more frequently in chemoproteomic datasets compared to the other DUBs. (b) C23 belongs to an intrinsically disordered region within OTUB1 as assessed by PONDR. (c) Covalent ligand screen of cysteine-reactive libraries competed against IA-rhodamine labeling of recombinant OTUB1 to identify binders to OTUB1 by gel-based ABPP. Vehicle DMSO or cysteine-reactive covalent ligands (50 μM) were pre-incubated with OTUB1 for 30 min at room temperature prior to IA-rhodamine labeling (500 nM, 30 min room temperature). OTUB1 was then separated by SDS/PAGE and in-gel fluorescence was assessed and quantified.