Ubiquitin: not just for proteasomes anymore.
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.
Aguilar
Rubén Claudio
RC
Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
Wendland
Beverly
B
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*
D009097:Multienzyme Complexes; D011956:Receptors, Cell Surface; D025801:Ubiquitin; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex