Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The energy-requirement for intracellular proteolysis is due largely to the involvement of large multimeric proteases whose function requires ATP hydrolysis. The best-studied such enzyme is protease La from E coli. This tetrameric protease is inhibited in vivo until the binding of an unfolded protein allostericically activates its peptidase and ATPase functions. This mechanism and tight transcriptional regulation prevent non-specific or excessive proteolysis. E. coli contains another ATP-hydrolyzing protease, Ti (Clp), which contains distinct ATPase and proteolytic subunits. Enzymes homologous to La and Ti exist in mitochondria and chloroplasts. In eukaryotic cells, a major neutral proteolytic activity is the 650 kDa proteasome. This multicatalytic structure can function as an ATP-dependent protease or as part of the ATP-dependent complex that degrades ubiquitinated proteins. In mammalian muscle this 1300 kDa complex is formed by an ATP-dependent association of the proteasome with another ATP-dependent protease complex, multipain. Much remains to be learned about the physiological roles and mechanisms of these novel proteases.
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PMID:ATP-dependent proteases in prokaryotic and eukaryotic cells. 210 93

On two-dimensional gel electrophoresis, proteasomes (multicatalytic proteinase complexes) from the yeast Saccharomyces cerevisiae were separated into a characteristic set of approximately 20 components with molecular weights of 21,000 to 31,000 and isoelectric points of 3.5 to 7.5. The main components were isolated by reverse-phase high performance liquid chromatography on a TSK gel phenyl-5PW RP column and named YC1 to YC11, in order of their elution. Immuno-blot analysis showed that two components (YC1-alpha and YC1-beta) with molecular weights of 30,800 and 28,300 strongly cross-reacted with antibody against the P-component of ATP-dependent protease Ti from Escherichia coli, but no components were found to react with antibodies against the A-component of protease Ti or another ATP-dependent protease La (the Ion gene product) of Escherichia coli. These results indicate a structural relationship between eukaryotic proteasomes and bacterial ATP-dependent protease Ti.
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PMID:Separation of yeast proteasome subunits. Immunoreactivity with antibodies against ATP-dependent protease Ti from Escherichia coli. 268 37

Lon protease, also known as protease La, is one of the simplest ATP-dependent proteases that plays vital roles in maintaining cellular functions by selectively eliminating misfolded, damaged and certain short-lived regulatory proteins. Although Lon is a homo-oligomer, each subunit of Lon contains both an ATPase and a protease active site. This relatively simple architecture compared to other hetero-oligomeric ATP-dependent proteases such as the proteasome makes Lon a useful paradigm for studying the mechanism of ATP-dependent proteolysis. In this article, we survey some recent developments in the mechanistic characterization of Lon with an emphasis on the utilization of pre-steady-state enzyme kinetic techniques to determine the timing of the ATPase and peptidase activities of the enzyme.
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PMID:Recent developments in the mechanistic enzymology of the ATP-dependent Lon protease from Escherichia coli: highlights from kinetic studies. 1721 28