| abstract |
A C-terminally modified Ubiquitin (Ub) derivative, ubiquitin vinyl sulfone (UbVS), which is specific for deubiquitinating enzymes (DUBs), was synthesized as an active site directed probe that irreversibly modifies a subset of Ub C-terminal hydrolases (UCHs) and Ub specific processing proteases (UBPs), is provided [125I]-UbVS modifies 6 of the 17 known and putative yeast deubiquitinating enzymes, namely Yuh1p, Ubp1p, Ubp2p, Ubp6p, Ubp12p and Ubp15p. In mammalian cells, a greater number of polypeptides is labeled, most of which are DUBs. An additional DUB that associates with the mammalian 26S proteasome, novel protein USP14, a mammalian homolog of yeast Ubp6p that is bound to the proteasome, is provided. |