Sumit Prakash

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Protein unfolding is a key step in several cellular processes, including protein translocation across some membranes and protein degradation by ATP-dependent proteases. ClpAP protease and the proteasome can actively unfold proteins in a process that hydrolyzes ATP. Here we show that these proteases seem to catalyze unfolding by processively unraveling their(More)
The proteasome is the main ATP-dependent protease in eukaryotic cells and controls the concentration of many regulatory proteins in the cytosol and nucleus. Proteins are targeted to the proteasome by the covalent attachment of polyubiquitin chains. The ubiquitin modification serves as the proteasome recognition element but by itself is not sufficient for(More)
Previous studies showed that the keratan sulfate-containing proteoglycans of bovine corneal stroma contain three unique core proteins designated 37A, 37B, and 25 (Funderburgh, J. L., Funderburgh, M. L., Mann, M. M., and Conrad, G. W. (1991) J. Biol. Chem. 266, 14226-14231). Degenerate oligonucleotides designed from amino acid sequences of the 37A protein(More)
The proteasome controls the turnover of many cellular proteins. Two structural features are typically required for proteins to be degraded: covalently attached ubiquitin polypeptides that allow binding to the proteasome and an unstructured region in the targeted protein that initiates proteolysis. Here, we have tested the degradation of model proteins to(More)
ATP-dependent proteases control the concentrations of hundreds of regulatory proteins and remove damaged or misfolded proteins from cells. They select their substrates primarily by recognizing sequence motifs or covalent modifications. Once a substrate is bound to the protease, it has to be unfolded and translocated into the proteolytic chamber to be(More)
Protein-protein pore interaction is a fundamental and ubiquitous process in biology and medical biotechnology. Here, we employed high-resolution time-resolved single-channel electrical recording along with protein engineering to examine a protein-protein pore interaction at single-molecule resolution. The pore was formed by Staphylococcus aureus(More)
Keratan sulfate proteoglycans (KSPGs) are the major proteoglycans of the cornea and are secreted by keratocytes in the corneal stroma. Previous studies have been able to show only transient secretion of KSPG in cell culture. In this study, cultures of bovine keratocytes were found to secrete the three previously characterized KSPG proteins into culture(More)
The proteasome controls many cellular processes by degrading a large number of regulatory proteins. Most proteins are targeted to the proteasome through covalent tagging by a chain consisting of several copies of the small protein ubiquitin. Finley and coworkers have now discovered two proteins, Hul5 and Ubp6, which regulate degradation further, when bound(More)
FtsH, a member of the AAA family of proteins, is the only membrane ATP-dependent protease universally conserved in prokaryotes, and the only essential ATP-dependent protease in Escherichia coli. We investigated the mechanism of degradation by FtsH. Other well-studied ATP-dependent proteases use ATP to unfold their substrates. In contrast, both in vitro and(More)
The eukaryotic 26S proteasome controls cellular processes by degrading specific regulatory proteins. Most proteins are targeted for degradation by a signal or degron that consists of two parts: a proteasome-binding tag, typically covalently attached polyubiquitin chains, and an unstructured region that serves as the initiation region for proteasomal(More)