Tandem Ubiquitin Binding Entities（TUBEs) capitalize on the linkage of multiple ubiquitin interacting motifs（UIMs) to generate reagents with high affinity for polyubiquitin. Biotin K63-TUBE binds K63-linked polyubiquitin with a 1000 to 10,000-fold preference for K63 over other linkage types and provides a sensitive and cost-effective tool for determining the abundance of K63-linked polyubiquitin in the cell, or identifying the linkage-type associated with a particular protein of interest. Based on an engineered peptide developed by Sims et al., Biotin K63-TUBE consists of multiple ubiquitin interacting motifs separated by rigid linkers, presumably increasing its affinity to extended K63 polyubiquitin chains. Biotin K63-TUBE is useful for detection and characterization of K63-linked polyubiquitylated proteins by Far Western blotting, affinity purification from lysates and biological fluids, and in situ detection.
