Human HR23A/Rad23A has two Ubiquitin-associated (UBA) motifs that can each bind Ubiquitin via a hydrophobic surface formed by residues located within the alpha 1 and alpha 3 helices of each UBA domain (1,2). Tandem-repeated Ubiquitin binding entities (TUBEs), which consist of multiple tandem Ubiquitin-binding UBA motifs, have been developed for the isolation and identification of ubiquitinated proteins (3). TUBEs show increased affinity for poly-Ubiquitin moieties compared to single UBA motifs (4). Additionally, TUBEs protect polyubiquitinated proteins from deubiquitylating enzymes, allowing for the detection of polyubiquitinated proteins at relatively low levels of abundance (5).
Detection with avidin-linked reagents allows for a higher efficiency and detection sensitivity than with other antibodies.
