The DCAF15 Intrachain TR-FRET Assay Kit is a sensitive high-throughput screening (HTS) TR-FRET Assay Kit designed to measure DCAF15 auto-ubiquitination activity in a homogeneous 384-reaction format. It utilizes Europium-labeled Ubiquitin (donor) and Cy5-labeled Ubiquitin (acceptor) to complete the TR-FRET pairing. This assay measures poly-ubiquitination since both the TR-FRET donor and acceptor are incorporated into poly-ubiquitin chains formed on DCAF15. As a homogenous assay, it requires no time-consuming washing steps, making it especially suitable for HTS applications as well as real-time kinetics analyses.