title: Ubiquitin: not just for proteasomes anymore.
abstract: Ubiquitin is a small protein that can be covalently linked to itself or other proteins, either as single ubiquitin molecules or as chains of polyubiquitin. Addition of ubiquitin to a target protein requires a series of enzymatic activities (by ubiquitin-activating, -conjugating and -ligating enzymes). The first function attributed to ubiquitin was the covalent modification of misfolded cytoplasmic proteins, thereby directing proteasome-dependent proteolysis. More recently, additional functions have been ascribed to ubiquitin and ubiquitin-related proteins. Ubiquitin directs specific proteins through the endocytic pathway by modifying cargo proteins, and possibly also components of the cytoplasmic protein trafficking machinery.
authors.affiliation: Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
authors.forename: Rubén Claudio
authors.initials: RC
authors.lastname: Aguilar
authors.forename: Beverly
authors.initials: B
authors.lastname: Wendland
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000818:Animals; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology; D005057:Eukaryotic Cells / Q000378:metabolism*; D006801:Humans; D009097:Multienzyme Complexes / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D021381:Protein Transport / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D009097:Multienzyme Complexes; D011956:Receptors, Cell Surface; D025801:Ubiquitin; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex