title: The emerging complexity of ubiquitin architecture.
abstract: Ubiquitylation is an essential post-translational modification (PTM) of proteins with diverse cellular functions. Polyubiquitin chains with different topologies have different cellular roles, and are referred to as a 'ubiquitin code'. Recent studies have begun to reveal that more complex ubiquitin architectures function as important signals in several biological pathways. These include PTMs of ubiquitin itself, such as acetylated ubiquitin and phospho-ubiquitin. Moreover, important roles for heterogeneous polyubiquitin chains, such as mixed or branched chains, have been reported, which significantly increase the diversity of the ubiquitin code. In this review, we describe mass spectrometry-based methods to characterize the ubiquitin signal. We also describe recent advances in our understanding of complex ubiquitin architectures, including our own findings concerning ubiquitin acetylation and branching within polyubiquitin chains.
authors.affiliation: Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Sciences, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Ohtake
authors.affiliation: Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Sciences, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Tsuchiya
mesh_terms: D000107:Acetylation; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008954:Models, Biological; D010766:Phosphorylation; D025821:Polyubiquitin; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction; D025801:Ubiquitin / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D025801:Ubiquitin; D025821:Polyubiquitin
keywords: acetylation; mass spectrometry; post-translational modification; signal transduction; ubiquitin