Ubiquitin

spinqualitylabelsall models Human ubiquitin (green) complex with ubiquitin-conjugating enzyme E2 (deep sky blue), 3k9p Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Function Ubiquitin (UBB) is found in almost all cells. It binds to proteins tagging them for destruction in the proteasome. UBB is activated by the UBB-activating enzymes E1, E2 and E3. Ubiquitin+1 is a frameshifted mutant of UBB observed in several diseases. A dimer of UBB (DiUBB) is formed by linkage of K48 to the C-terminus of a second UBB molecule. Polyubiquitin (polyUBB) is a chain of ubiquitin molecules bound by peptide bonds. PolyUBB can be formed by lysine residues: K6, K11, K27, 29, K33, K48, and K63. Different lysine linkages convey different functions to polyUBB. Lys48- linked polyUBB and LYs11-linked polyUBB are associated with proteasome degradation; Lys63-linked and Lys-6 polyUBB are associated with non-proteolytic functions. At least 4 UBB molecules are needed to tag a protein for the proteasome. Human ubiquitin interactions with ubiquitin-conjugating enzyme E2 (3k9p). For details see Ubiquitin Structure & Function Ubiquitin and Ubiquitination Ubiquitin salt bridge discussion Ubiquitin chains. Professors Ciechanover, Hershko and Rose received the Nobel Prize in 2004 for their discovery of the process by which ubiquitin mediates protein proteolysis. Additional Resources See also: Tumor susceptibility gene 101 SUMO Disease The UBB-proteasome system deregulation has been implicated in the pathogenesis of many neurodegenerative disorders like Alzheimer's disease, Parkinson disease, Huntington disease, Prion-like lethal disorders and in genetic diseases like cystic fibrosis, angelman's syndrome, Liddle syndrome and many cancers.

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