Role(s) of Cdc48/p97 in mitosis

2008 ◽  
Vol 36 (1) ◽  
pp. 126-130 ◽  
Author(s):  
Hemmo Meyer ◽  
Oliver Popp
Keyword(s):  
Cellular Structures ◽  
Regulatory Processes ◽  
Binding Partners ◽  
Basic Activity ◽  
Cell Divison ◽  
Substrate Proteins ◽  
Ubiquitinated Substrate ◽  
General Perspective

The ubiquitin-dependent chaperone Cdc48 (cell divison cycle 48)/p97 is involved in a variety of degradative and regulatory processes during interphase that help to maintain cellular homoeostasis. The results available so far suggest that its basic activity is to mobilize ubiquitinated substrate proteins from cellular structures or segregate them from binding partners, and then hand them over for degradation or recycling. Several studies in different organisms show that Cdc48/p97 also has critical roles in mitosis. However, many important aspects of these functions and the general perspective have remained unclear.

scholarly journals Structural basis for the recognition of K48-linked Ub chain by proteasomal receptor Rpn13

2019 ◽  
Author(s):  
Zhu Liu ◽  
Xu Dong ◽  
Hua-Wei Yi ◽  
Ju Yang ◽  
Zhou Gong ◽  
...  
Keyword(s):  
Single Molecule ◽  
Complex Structure ◽  
Binding Mode ◽  
Structural Basis ◽  
Ubiquitinated Proteins ◽  
Single Molecule Fret ◽  
Compact State ◽  
A Charge ◽  
Substrate Proteins ◽  
Ubiquitinated Substrate

ABSTRACTThe interaction between K48-linked ubiquitin (Ub) chain and Rpn13 is important for proteasomal degradation of ubiquitinated substrate proteins. Only the complex structure between the N-terminal domain of Rpn13 (Rpn13NTD) and Ub monomer has been characterized, and it remains unclear how Rpn13 specifically recognizes K48-linked Ub chain. Using single-molecule FRET, here we show that K48-linked diubiquitin (K48-diUb) fluctuates among three distinct conformational states, and a preexisting compact state is selectively enriched by Rpn13NTD. The same binding mode is observed for full-length Rpn13 and longer K48-linked Ub chain. Using solution NMR spectroscopy, we have solved the complex structure between Rpn13NTD and K48-diUb. In the structure, Rpn13NTD simultaneously interacts with proximal and distal Ub subunits of K48-diUb that remain associated in the complex, thus corroborating smFRET findings. The proximal Ub interacts with Rpn13NTD similarly as the Ub monomer in the known Rpn13NTD:Ub structure, while the distal Ub binds to a largely electrostatic surface of Rpn13NTD. Thus, a charge reversal mutation in Rpn13NTD can weaken the interaction between Rpn13 and K48-linked Ub chain, causing accumulation of ubiquitinated proteins. Moreover, blockage of the access of the distal Ub to Rpn13NTD with a proximity attached Ub monomer can also disrupt the interaction between Rpn13 and K48-diUb. Together, the bivalent interaction of K48-linked Ub chain with Rpn13 provides the structural basis for Rpn13 linkage selectivity, which opens a new window for modulating proteasomal function.

scholarly journals Mechanism of Hsp70 specialized interactions in protein translocation and the unfolded protein response

Open Biology ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 200089
Author(s):  
Natacha Larburu ◽  
Christopher J. Adams ◽  
Chao-Sheng Chen ◽  
Piotr R. Nowak ◽  
Maruf M. U. Ali
Keyword(s):  
Unfolded Protein Response ◽  
Protein Translocation ◽  
Cellular Functions ◽  
Binding Partner ◽  
Unfolded Protein ◽  
Binding Partners ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Substrate Proteins ◽  
Partner Proteins

Hsp70 chaperones interact with substrate proteins in a coordinated fashion that is regulated by nucleotides and enhanced by assisting cochaperones. There are numerous homologues and isoforms of Hsp70 that participate in a wide variety of cellular functions. This diversity can facilitate adaption or specialization based on particular biological activity and location within the cell. In this review, we highlight two specialized binding partner proteins, Tim44 and IRE1, that interact with Hsp70 at the membrane in order to serve their respective roles in protein translocation and unfolded protein response signalling. Recent mechanistic data suggest analogy in the way the two Hsp70 homologues (BiP and mtHsp70) can bind and release from IRE1 and Tim44 upon substrate engagement. These shared mechanistic features may underlie how Hsp70 interacts with specialized binding partners and may extend our understanding of the mechanistic repertoire that Hsp70 chaperones possess.

Preparatory Procedures for Electron Microscopic Analysis at the Molecular Level of Resolution

1978 ◽  
Vol 36 (3) ◽  
pp. 516-520
Author(s):  
F.J. Sjostrand
Keyword(s):  
Electron Microscope ◽  
Molecular Level ◽  
Microscopic Analysis ◽  
Resolving Power ◽  
Cellular Structures ◽  
Electron Microscopic ◽  
Systematic Analysis ◽  
Technical Developments ◽  
Thin Sectioning ◽  
Obvious Reason

In the 1940's and 1950's electron microscopy conferences were attended with everybody interested in learning about the latest technical developments for one very obvious reason. There was the electron microscope with its outstanding performance but nobody could make very much use of it because we were lacking proper techniques to prepare biological specimens. The development of the thin sectioning technique with its perfectioning in 1952 changed the situation and systematic analysis of the structure of cells could now be pursued. Since then electron microscopists have in general become satisfied with the level of resolution at which cellular structures can be analyzed when applying this technique. There has been little interest in trying to push the limit of resolution closer to that determined by the resolving power of the electron microscope.

Some aspects of the defect structure in an austenitic stainless steel

1978 ◽  
Vol 36 (1) ◽  
pp. 314-315
Author(s):  
R. Gonzalez ◽  
L. Bru
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cellular Structures ◽  
Total Strain Amplitude ◽  
Total Deformation ◽  
Density Of Dislocations ◽  
Planar Arrays ◽  
Stacking Fault Tetrahedra ◽  
Distribution Of Dislocations ◽  
Very High

The analysis of stacking fault tetrahedra (SFT) in fatigued metals (1,2) is somewhat complicated, due partly to their relatively low density, but principally to the presence of a very high density of dislocations which hides them. In order to overcome this second difficulty, we have used in this work an austenitic stainless steel that deforms in a planar mode and, as expected, examination of the substructure revealed planar arrays of dislocation dipoles rather than the cellular structures which appear both in single and polycrystals of cyclically deformed copper and silver. This more uniform distribution of dislocations allows a better identification of the SFT.The samples were fatigue deformed at the constant total strain amplitude Δε = 0.025 for 5 cycles at three temperatures: 85, 293 and 773 K. One of the samples was tensile strained with a total deformation of 3.5%.

Intraindividual Variability and Stability of Affect and Well-Being

GeroPsych ◽  
2013 ◽  
Vol 26 (3) ◽  
pp. 185-199 ◽  
Author(s):  
Christina Röcke ◽  
Annette Brose
Keyword(s):  
Age Differences ◽  
Well Being ◽  
Subjective Well Being ◽  
Emotional Experiences ◽  
Short Term ◽  
Regulatory Processes ◽  
Functional Implications ◽  
Methodological Approaches ◽  
Underlying Processes

Whereas subjective well-being remains relatively stable across adulthood, emotional experiences show remarkable short-term variability, with younger and older adults differing in both amount and correlates. Repeatedly assessed affect data captures both the dynamics and stability as well as stabilization that may indicate emotion-regulatory processes. The article reviews (1) research approaches to intraindividual affect variability, (2) functional implications of affect variability, and (3) age differences in affect variability. Based on this review, we discuss how the broader literature on emotional aging can be better integrated with theories and concepts of intraindividual affect variability by using appropriate methodological approaches. Finally, we show how a better understanding of affect variability and its underlying processes could contribute to the long-term stabilization of well-being in old age.

Topologiacl Models of 2D Fractal Cellular Structures

1995 ◽  
Vol 5 (11) ◽  
pp. 1417-1429 ◽  
Author(s):  
G. Le Caër ◽  
R. Delannay
Keyword(s):  
Cellular Structures

PERMEABILITY OF CELLS AND ITS IMPORTANCE IN ASSESSMENT OF FISHES AGE

1970 ◽  
pp. 70-73
Author(s):  
N. I. Maslova
Keyword(s):  
Cholesterol Content ◽  
The Body ◽  
Cellular Structures ◽  
Ratio Estimation ◽  
Carbohydrate Diet ◽  
Spawning Period ◽  
Age Related ◽  
Experimental Base ◽  
Cellular Permeability ◽  
Membrane Strength

The article presents analysis of material and results of their own studies on changes in the permeability of cellular structures, organs and tissues in carp, which is of great importance in determining age-related indicators. The cells permeability in liver and gonads estimation was carried out under the experimental base of VNIIR on two carp genotypes during the pre-spawning period. The carp groups taken for analysis differed significantly in their genotypes. In females of the Khrapunov group the fecundity was 2023.0 thousand units, while the number of oocytes filled with yolk was only 0.7%, in the Ostashevsky ones - 1370.0 thousand units and 8.6%, respectively. During estimation the chemical composition of the generative tissue in females and males it was established that the cholesterol and lecithin content in males is higher than that of females, while feeding dependence is observed, especially on the amount of protein in the diet. For example, in females on protein diet contained less glycogen in gonads than on females on carbohydrate diet. Lecithin and cholesterol are higher in males than in females, which corresponds to increasing the Gyurdy Ratio (estimation of cell membrane strength). In spermatogenesis the content of phospholipids and cholesterol in the liver was decreased less than during ovogenesis. This indicates a lower level of synthetic processes in the milts compared with the ovaries. The cholesterol content in sperm is higher than in caviar in 19.6 times, and phospholipids almost doubled. With increasing age, the Gyordy Ratio for caviar decreases, for sperm it increases, the percentage of caviar fertilization increases. As the body age metabolism deteriorates, cellular permeability decreases (the ratio of lecithin and cholesterol changes significantly). At the same time, the permeability of cells in different organs and tissues varies and depends on living conditions, especially feeding and to some extent on the origin. In fish the gross productivity decreases as growth slows down and more energy is spent on adaptation to environmental conditions.

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