scholarly journals Ubiquitin-specific Cysteine Protease 2a (USP2a) Regulates the Stability of Aurora-A

2011 ◽  
Vol 286 (45) ◽  
pp. 38960-38968 ◽  
Author(s):  
Yan Shi ◽  
Larry R. Solomon ◽  
Ana Pereda-Lopez ◽  
Vincent L. Giranda ◽  
Yan Luo ◽  
...  
Keyword(s):  
Cysteine Protease ◽  
Aurora A ◽  
The Stability ◽  
Protease 2A

scholarly journals Protein phosphatase 6 regulates mitotic spindle formation by controlling the T-loop phosphorylation state of Aurora A bound to its activator TPX2

2010 ◽  
Vol 191 (7) ◽  
pp. 1315-1332 ◽  
Author(s):  
Kang Zeng ◽  
Ricardo Nunes Bastos ◽  
Francis A. Barr ◽  
Ulrike Gruneberg
Keyword(s):  
Protein Phosphatase ◽  
Aurora A ◽  
Spindle Formation ◽  
Regulatory Subunits ◽  
Kinase Activation ◽  
Activator Proteins ◽  
Mitotic Kinase ◽  
General Importance ◽  
The Stability

Many protein kinases are activated by a conserved regulatory step involving T-loop phosphorylation. Although there is considerable focus on kinase activator proteins, the importance of specific T-loop phosphatases reversing kinase activation has been underappreciated. We find that the protein phosphatase 6 (PP6) holoenzyme is the major T-loop phosphatase for Aurora A, an essential mitotic kinase. Loss of PP6 function by depletion of catalytic or regulatory subunits interferes with spindle formation and chromosome alignment because of increased Aurora A activity. Aurora A T-loop phosphorylation and the stability of the Aurora A–TPX2 complex are increased in cells depleted of PP6 but not other phosphatases. Furthermore, purified PP6 acts as a T-loop phosphatase for Aurora A–TPX2 complexes in vitro, whereas catalytically inactive mutants cannot dephosphorylate Aurora A or rescue the PPP6C depletion phenotype. These results demonstrate a hitherto unappreciated role for PP6 as the T-loop phosphatase regulating Aurora A activity during spindle formation and suggest the general importance of this form of regulation.

Cathepsin B Stability, But Not Activity, Is Affected in Cysteine:Cystine Redox Buffers

2002 ◽  
Vol 383 (7-8) ◽  
pp. 1199-1204 ◽  
Author(s):  
C. S. Pillay ◽  
C. Dennison
Keyword(s):  
Redox Potential ◽  
Cysteine Protease ◽  
Cathepsin B ◽  
Reduction Potential ◽  
Potential Range ◽  
Neutral Ph ◽  
Lysosomal Cysteine Protease ◽  
The Stability ◽  
Redox Buffers

Abstract In order to test the hypothesis that the lysosomal cysteine protease cathepsin B may be redox regulated in vivo, cathepsin B activity and stability were measured in cysteine and/or cystinecontaining buffers. Cathepsin B activity in cysteinecontaining buffers was similar at pH 6.0 and pH 7.0, over all thiol concentrations tested. In contrast, the stability of the enzyme was greater at pH 6.0 than at pH 7.0. This suggests that the enzymes operational pH in vivo may be < pH 7.0. The activity of the enzyme was depressed in glutathionecontaining buffers. When assessed in cysteine:cystine redox buffers (pH 6.0 7.0) cathepsin B was active over a broad redox potential range, suggesting that cathepsin B activity may not be redox regulated. However, at pH 7.0, the stability of cathepsin B decreased with increasing reduction potential and ambient cystine concentration. This suggests that the stability of the enzyme at neutral pH is dependent on redox potential, and on the presence of oxidising agents.

Aurora A kinase interacts with and phosphorylates VHL protein

Biologia ◽  
2012 ◽  
Vol 67 (5) ◽  
Author(s):  
Imen Ferchichi ◽  
Yannick Arlot ◽  
Jean-Yves Cremet ◽  
Claude Prigent ◽  
Amel Benammar Elgaaied
Keyword(s):  
Mitotic Spindle ◽  
Aurora A Kinase ◽  
Aurora A ◽  
Hek 293 ◽  
Von Hippel Lindau ◽  
Cell Extracts ◽  
Vhl Protein ◽  
The Stability

AbstractThe serine/threonin kinase Aurora A is an oncoprotein, whereas von Hippel-Lindau protein (pVHL) is a tumor suppressor protein. Both proteins have the same localization during mitosis: in the mitotic spindle and the centrosome. These two proteins also have common functions, such as the regulation of the cell cycle, the stability of the mitotic spindle and both intervene in the functioning of centrosomes. In this study we have analyzed the interaction between Aurora A and pVHL with immunoprecipitation and in vitro phosphorylation experiments. We have confirmed that the immunoprecipitation of pVHL from Hek 293 cell extracts were coupled with Aurora A. In addition, the interaction between the two proteins has been tested by analyzing the phosphorylation of pVHL in vitro by Aurora A. The results revealed that pVHL was phosphorylated by Aurora A. In conclusion, the study demonstrated that Aurora A interacts with and phosphorylates pVHL. Given the role of these two proteins in cell division as well as their status in cancer, this interaction requires further investigation.

scholarly journals Phosphorylation, Mg-ADP, and Inhibitors Differentially Shape the Conformational Dynamics of the A-Loop of Aurora-A

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 567
Author(s):  
Zahra Musavizadeh ◽  
Alessandro Grottesi ◽  
Giulia Guarguaglini ◽  
Alessandro Paiardini
Keyword(s):  
Protein Kinases ◽  
Kinase Inhibitors ◽  
Conformational Dynamics ◽  
Md Simulations ◽  
Kinase Domain ◽  
General Description ◽  
Aurora A ◽  
Post Translational Modification ◽  
The Stability

The conformational state of the activation loop (A-loop) is pivotal for the activity of most protein kinases. Hence, the characterization of the conformational dynamics of the A-loop is important to increase our understanding of the molecular processes related to diseases and to support the discovery of small molecule kinase inhibitors. Here, we carry out a combination of molecular dynamics (MD) and essential dynamics (ED) analyses to fully map the effects of phosphorylation, ADP, and conformation disrupting (CD) inhibitors (i.e., CD532 and MLN8054) on the dynamics of the A-loop of Aurora-A. MD revealed that the stability of the A-loop in an open conformation is enhanced by single phospho-Thr-288, while paradoxically, the presence of a second phosphorylation at Thr-287 decreases such stability and renders the A-loop more fluctuant in time and space. Moreover, we found that this post-translational modification has a significant effect on the direction of the A-loop motions. ED analysis suggests that the presence of the phosphate moiety induces the dynamics of Aurora-A to sample two distinct energy minima, instead of a single large minimum, as in unphosphorylated Aurora-A states. This observation indicates that the conformational distributions of Aurora-A with both single and double phospho-threonine modifications are remarkably different from the unphosphorylated state. In the closed states, binding of CD532 and MLN8054 inhibitors has the effect of increasing the distance of the N- and C-lobes of the kinase domain of Aurora-A, and the angle analysis between those two lobes during MD simulations showed that the N- and C-lobes are kept more open in presence of CD532, compared to MLN8054. As the A-loop is a common feature of Aurora protein kinases, our studies provide a general description of the conformational dynamics of this structure upon phosphorylation and different ligands binding.

scholarly journals Characterization of Thermo- and Detergent Stable Antigenic Glycosylated Cysteine Protease ofEuphorbia nivuliaBuch.-Ham. and Evaluation of Its Ecofriendly Applications

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Shamkant B. Badgujar ◽  
Raghunath T. Mahajan
Keyword(s):  
Cysteine Protease ◽  
Meloidogyne Incognita ◽  
Potential Role ◽  
Root Knot Nematode ◽  
X Ray ◽  
Leather Processing ◽  
Quality Product ◽  
The Stability ◽  
Hydrolysis Of

An antigenic glycosylated cysteine protease has been purified from the latex ofEuphorbia nivuliaBuch.-Ham. It exhibits remarkable protease activity in the presence of metal ions, oxidizing agents, organic solvents, and detergents. This enzyme showed potential role in leather processing industry due to its dehairing activity for animal hide without hydrolyzing fibrous proteins, producing, by this way, a better quality product. The enzyme can also be used for silver recovering from X-ray plates. In addition, the stability (temperature and surfactants) and hydrolysis of blood stain data also revealed its application in detergent industries. Agriculturally, this protease finds application in biocontrol process against the infectious management of root knot nematode,Meloidogyne incognita. Biologically, it shows noticeable wound healing, haemostatic and antibacterial activity.

Open discussion

1982 ◽  
Vol 99 ◽  
pp. 605-613
Author(s):  
P. S. Conti
Keyword(s):  
Buenos Aires ◽  
Large Mass ◽  
List Type ◽  
Common Phenomenon ◽  
Open Discussion ◽  
The Stability ◽  
Ring Nebulae

Conti: One of the main conclusions of the Wolf-Rayet symposium in Buenos Aires was that Wolf-Rayet stars are evolutionary products of massive objects. Some questions:–Do hot helium-rich stars, that are not Wolf-Rayet stars, exist?–What about the stability of helium rich stars of large mass? We know a helium rich star of ∼40 MO. Has the stability something to do with the wind?–Ring nebulae and bubbles : this seems to be a much more common phenomenon than we thought of some years age.–What is the origin of the subtypes? This is important to find a possible matching of scenarios to subtypes.

Symmetric Multistep Methods Revisited: II. Numerical Experiments

1999 ◽  
Vol 173 ◽  
pp. 309-314 ◽  
Author(s):  
T. Fukushima
Keyword(s):  
Multistep Methods ◽  
Computational Time ◽  
Integration Time ◽  
Implicit Methods ◽  
Symmetric Methods ◽  
Celestial Bodies ◽  
The Stability ◽  
Predictor Corrector ◽  
Symmetric Multistep Methods ◽  
Integration Errors

AbstractBy using the stability condition and general formulas developed by Fukushima (1998 = Paper I) we discovered that, just as in the case of the explicit symmetric multistep methods (Quinlan and Tremaine, 1990), when integrating orbital motions of celestial bodies, the implicit symmetric multistep methods used in the predictor-corrector manner lead to integration errors in position which grow linearly with the integration time if the stepsizes adopted are sufficiently small and if the number of corrections is sufficiently large, say two or three. We confirmed also that the symmetric methods (explicit or implicit) would produce the stepsize-dependent instabilities/resonances, which was discovered by A. Toomre in 1991 and confirmed by G.D. Quinlan for some high order explicit methods. Although the implicit methods require twice or more computational time for the same stepsize than the explicit symmetric ones do, they seem to be preferable since they reduce these undesirable features significantly.

Uniformity of Magnification from Different Electron Microscopes

1967 ◽  
Vol 25 ◽  
pp. 32-33
Author(s):  
Godfrey C. Hoskins ◽  
V. Williams ◽  
V. Allison
Keyword(s):  
Diffraction Grating ◽  
The Other ◽  
Carbon Replica ◽  
Electron Microscopes ◽  
The Stability

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.

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