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Ubiquitin: not just for proteasomes anymore

2003; Elsevier BV; Volume: 15; Issue: 2 Linguagem: Inglês

10.1016/s0955-0674(03)00010-3

1879-0410

R. Claudio Aguilar, Beverly Wendland,

Endoplasmic Reticulum Stress and Disease

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.