Figure 1.

Experiment workflow. A) Control and AD human postmortem frontal cortex brain tissues (n=5 each group) were homogenized in 8M urea lysis buffer. For both global and ubiquitylome analysis, brain protein extracts from each sample was first denatured, alkylated and proteolytically digested followed by peptide desalting as described in methods. For global proteome analysis, peptides were analyzed by LC-MS/MS on Orbitrap Fusion Tribrid mass spectrometer. For brain ubiquitylome analysis, peptides were subjected to di-Gly affinity enrichment as described in methods followed by LC-MS/MS analysis in replicate on an Orbitrap Fusion Tribrid mass spectrometer. Protein abundance was calculated by peptide ion-intensity measurements across LC-MS runs using the label free quantification (LFQ) algorithm in MaxQuant.