نتایج جستجو برای: ubiquitin
تعداد نتایج: 28509 فیلتر نتایج به سال:
Ubiquitin carboxyl-terminal hydrolase (formerly known as ubiquitin carboxyl-terminal esterase), from rabbit reticulocytes, has been shown to hydrolyze thiol esters formed between the ubiquitin carboxyl terminus and small thiols (e.g. glutathione), as well as free ubiquitin adenylate (Rose, I. A., and Warms, J. V. B. (1983) Biochemistry 22, 4234-4237). We now show that this enzyme hydrolyzes ami...
The ubiquitin system regulates virtually all aspects of cellular function. We report a method to target the myriad enzymes that govern ubiquitination of protein substrates. We used massively diverse combinatorial libraries of ubiquitin variants to develop inhibitors of four deubiquitinases (DUBs) and analyzed the DUB-inhibitor complexes with crystallography. We extended the selection strategy t...
The protein ubiquitin is a covalent modifier of proteins, including itself. The ubiquitin system encompasses the enzymes required for catalysing attachment of ubiquitin to substrates as well as proteins that bind to ubiquitinated proteins leading them to their final fate. Also included are activities that remove ubiquitin independent of, or in concert with, proteolysis of the substrate, either ...
Ubiquitination of a subset of proteins by ubiquitin chain elongation factors (E4), represented by Ufd2p in Saccharomyces cerevisiae, is a pivotal regulator for many biological processes. However, the mechanism of Ufd2p-mediated ubiquitination is largely unclear. Here, we show that Ufd2p catalyses K48-linked multi-monoubiquitination on K29-linked ubiquitin chains assembled by the ubiquitin ligas...
As a ubiquitin-like modifier, ISG15 is conjugated to many cellular proteins in a process termed protein ISGylation. However, the crosstalk between protein ISGylation and the ubiquitin proteasome system is not fully understood. Here, we report that cellular ubiquitin is a substrate of ISG15 and Lys 29 on ubiquitin is the major ISG15 acceptor site. Using a model substrate, we demonstrate that ISG...
Ubiquitin-dependent protein degradation is essential for cells to survive many environmental stresses. Thus, it may be necessary to buffer ubiquitin and proteasome pools against fluctuation. Proteasome levels are tightly regulated, and proteasome deficiency stimulates a stress response. Here we report a novel pathway of cellular response to ubiquitin depletion. Unlike proteasome stress, ubiquit...
Any of seven lysine residues on ubiquitin can serve as the base for chain-extension, resulting in a sizeable spectrum of ubiquitin modifications differing in chain length or linkage type. By optimizing a procedure for rapid lysis, we charted the profile of conjugated cellular ubiquitin directly from whole cell extract. Roughly half of conjugated ubiquitin (even at high molecular weights) was no...
Despite its central role in protein degradation little is known about the molecular mechanisms that sense, maintain, and regulate steady state concentration of ubiquitin in the cell. Here, we describe a novel mechanism for regulation of ubiquitin homeostasis that is mediated by phosphorylation of ubiquitin at the Ser57 position. We find that loss of Ppz phosphatase activity leads to defects in ...
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