title: What's Ub chain linkage got to do with it?
abstract: Ubiquitination-the covalent conjugation of ubiquitin (Ub) to other cellular proteins-regulates a wide range of cellular processes. Often, multiple Ub molecules are added to the substrate to form a Ub chain. Distinct outcomes have been observed for substrates modified with multi-Ub chains linked through particular lysine residues. However, recent studies suggest that Ub chain linkages may not be the key determinant for substrate fate. Here, we review evidence suggesting that Ub-binding proteins play a pivotal role in determining the outcome of substrate ubiquitination. In fulfilling their functions in proteasome-mediated proteolysis or signaling, Ub receptors link ubiquitinated proteins to downstream molecules through protein-protein interactions. Studies of Ub-binding factors may therefore hold the key to understanding the diverse functions of the Ub molecule.
authors.affiliation: Institute of Biotechnology, Department of Molecular Medicine, University of Texas Health Science Center, San Antonio, TX 78245, USA.
authors.forename: Ikjin
authors.initials: I
authors.lastname: Kim
authors.forename: Hai
authors.initials: H
authors.lastname: Rao
mesh_terms: D002352:Carrier Proteins; D008954:Models, Biological; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex