Fig. 1.

Methods to identify substrates of E3 ligase. Classes of E3s are indicated in the center, and techniques and approaches for the identification of substrates are categorized as follows (orange boxes): pull-downs coupled with in vitro ubiquitylation reactions; cell-based screens; co-immunoprecipitations (Co-IPs) or affinity purification (AP) of the E3; and substrate traps. Examples of techniques covered under these subcategories are circled