This project includes two separate experiments where the ubiquitylated proteome of the budding yeast Saccharomyces cerevisiae was enriched from whole cell lysate by affinity purification using a novel OtUBD affinity resin. In the first experiment, two distinct experimental conditions (native, denaturing) were used to compare the proteins enriched by OtUBD affinity resin and the negative control resin. In the second experiment, the ubiquitylation profile of proteins were compared among wildtype yeast cells and yeasts lacking certain E3 ligase enzymes.