E3 ligases remain among the most difficult enzyme targets to assay and discover potent therapeutic applications, possibly due to their dependence on upstream E1 and E2 enzymes for the activation and transfer of ubiquitin. As a result, traditional assays for E3 ligases are complex and prone to off-target false positives. At LifeSensors, we have developed reagents and assays encompassing both traditional and non-traditional approaches for E3 ligase screening and profiling. Quickly distinguishing true hits from false positives, developing structure-activity relationships, and establishing rank order potency from purified enzymes to cellular models are key steps to success. LifeSensors brings together the tools and expertise necessary to overcome the many pitfalls in the E3 ligase field.
Our E3 TR-FRET detection system utilizes our TUBE technology to monitor E3 ligase activity by fluorescence signal. This assay involves donor -labeled TUBEs that bind to acceptor-labelled polyubiquitin chains synthesized by the target E3 ligase. When Donor labelled TUBEs come in close proximity to polyubiquitin chains containing acceptor-labeled ubiquitin will yield in a FRET signal. This signal can be monitored over time in a homogenous, high-throughput format, making it ideal for small-molecule screening to find tool compounds for E3 ligases.