- Future Directions in Studies of Motor Proteins and Molecular Motors

2015 ◽  
pp. 200-205
Keyword(s):  
Molecular Motors ◽  
Motor Proteins ◽  
Future Directions

The Kar3p and Kip2p motors function antagonistically at the spindle poles to influence cytoplasmic microtubule numbers

1998 ◽  
Vol 111 (3) ◽  
pp. 295-301 ◽  
Author(s):  
A. Huyett ◽  
J. Kahana ◽  
P. Silver ◽  
X. Zeng ◽  
W.S. Saunders
Keyword(s):  
Molecular Motors ◽  
Motor Proteins ◽  
Single Gene ◽  
Intermediate Phenotype ◽  
Microtubule Network ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cytoplasmic Microtubule ◽  
Spindle Poles ◽  
Microtubule Motors ◽  
Microtubule Growth

Microtubules provide the substrate for intracellular trafficking by association with molecular motors of the kinesin and dynein superfamilies. Motor proteins are generally thought to function as force generating units for transport of various cargoes along the microtubule polymer. Recent work suggests additional roles for motor proteins in changing the structure of the microtubule network itself. We report here that in the budding yeast Saccharomyces cerevisiae microtubule motors have antagonistic effects on microtubule numbers and lengths. As shown previously, loss of the Kar3p motor stimulates cytoplasmic microtubule growth while loss of Kip2p leads to a sharp reduction in cytoplasmic microtubule numbers. Loss of both the Kip2p and Kar3p motors together in the same cell produces an intermediate phenotype, suggesting that these two motors act in opposition to control cytoplasmic microtubule density. A Kip2p-GFP fusion from single gene expression is most concentrated at the spindle poles, as shown previously for an epitope tagged Kar3p-HA, suggesting both of these motors act from the minus ends of the microtubules to influence microtubule numbers.

Dynamics of microtubules, motor proteins and 20S proteasomes during bovine oocyte IVM

2009 ◽  
Vol 21 (2) ◽  
pp. 304 ◽  
Author(s):  
S. E. Racedo ◽  
M. C. Branzini ◽  
D. Salamone ◽  
C. Wójcik ◽  
V. Y. Rawe ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Molecular Motors ◽  
Motor Proteins ◽  
Chromatin Condensation ◽  
Germinal Vesicle ◽  
Cytoplasmic Dynein ◽  
Developmental Competence ◽  
Bovine Oocyte ◽  
Sodium Orthovanadate ◽  
Female Meiosis

The present study investigated the distribution of cytoplasmic dynein, dynactin and 20S proteasomes in oocytes isolated from small (<2 mm) and large (2–8 mm) follicles during IVM. Immediately after chromatin condensation (germinal vesicle (GV) breakdown), dynactin was closely associated with the chromatin and interacted with tubulin at the MI and MII spindles in oocytes recovered from large follicles. Dynactin showed perinuclear concentration. Dynein was homogeneously distributed in the cytoplasm of GV oocytes in both groups and was associated with the chromatin at the MI and MII spindle. The 20S proteasomes were found predominantly in the nucleus at the GV stage and were associated with the chromatin up to the MII stage in both groups of oocytes. The use of sodium orthovanadate, an inhibitor or phosphatase and ATPase activity, and nocodazole, a known disruptor of microtubules, affected the localisation of proteasomes in the meiotic stages. The results demonstrate the distinct dynamics of molecular motors and proteasomes during bovine oocyte IVM, their possible relationship with the developmental competence of the oocyte and the link between microtubules, their associated molecular motors and the transport of proteasomes during bovine female meiosis.

scholarly journals Large-scale chirality in an active layer of microtubules and kinesin motor proteins

Soft Matter ◽  
2018 ◽  
Vol 14 (17) ◽  
pp. 3221-3231 ◽  
Author(s):  
Kyongwan Kim ◽  
Natsuhiko Yoshinaga ◽  
Sanjib Bhattacharyya ◽  
Hikaru Nakazawa ◽  
Mitsuo Umetsu ◽  
...  
Keyword(s):  
Active Layer ◽  
Molecular Motors ◽  
Glass Surface ◽  
Large Scale ◽  
Motor Proteins ◽  
Kinesin Motor ◽  
Kinesin Motor Proteins

The large scale active chiral rotation of aligned microtubules is driven by kinesin molecular motors on a glass surface.

scholarly journals Poleward transport of Eg5 by dynein–dynactin in Xenopus laevis egg extract spindles

2008 ◽  
Vol 182 (4) ◽  
pp. 715-726 ◽  
Author(s):  
Marianne Uteng ◽  
Christian Hentrich ◽  
Kota Miura ◽  
Peter Bieling ◽  
Thomas Surrey
Keyword(s):  
Cell Division ◽  
Xenopus Laevis ◽  
Molecular Motors ◽  
Motor Proteins ◽  
Motor Protein ◽  
Spindle Assembly ◽  
Cross Linking ◽  
Motor Movement ◽  
Spindle Poles ◽  
Egg Extract

Molecular motors are required for spindle assembly and maintenance during cell division. How motors move and interact inside spindles is unknown. Using photoactivation and photobleaching, we measure mitotic motor movement inside a dynamic spindle. We find that dynein–dynactin transports the essential motor Eg5 toward the spindle poles in Xenopus laevis egg extract spindles, revealing a direct interplay between two motors of opposite directionality. This transport occurs throughout the spindle except at the very spindle center and at the spindle poles, where Eg5 remains stationary. The variation of Eg5 dynamics with its position in the spindle is indicative of position-dependent functions of this motor protein. Our results suggest that Eg5 drives microtubule flux by antiparallel microtubule sliding in the spindle center, whereas the dynein-dependent concentration of Eg5 outside the spindle center could contribute to parallel microtubule cross-linking. These results emphasize the importance of spatially differentiated functions of motor proteins and contribute to our understanding of spindle organization.

scholarly journals Forced desorption of semiflexible polymers, adsorbed and driven by molecular motors

Soft Matter ◽  
2016 ◽  
Vol 12 (7) ◽  
pp. 2157-2165 ◽  
Author(s):  
Abhishek Chaudhuri ◽  
Debasish Chaudhuri
Keyword(s):  
Molecular Motors ◽  
Motor Proteins ◽  
Semiflexible Polymers ◽  
Pulling Force

We formulate and characterize a model to describe the dynamics of semiflexible polymers in the presence of activity due to motor proteins attached irreversibly to a substrate, and a transverse pulling force acting on one end of the filament.

scholarly journals PI31 is an adaptor protein for proteasome transport in axons and required for synaptic development and function

2018 ◽  
Author(s):  
Kai Liu ◽  
Sandra Jones ◽  
Adi Minis ◽  
Jose Rodriguez ◽  
Henrik Molina ◽  
...  
Keyword(s):  
Molecular Motors ◽  
Motor Proteins ◽  
Neuronal Development ◽  
Adaptor Protein ◽  
Ubiquitin Proteasome System ◽  
P38 Map Kinase ◽  
Dynein Light Chain ◽  
Root Cause ◽  
Ubiquitin Proteasome ◽  
And Function

AbstractProtein degradation by the ubiquitin-proteasome system (UPS) is critical for neuronal development, plasticity and function. Neurons utilize microtubule-dependent molecular motors to allocate proteasomes to synapses, but how proteasomes are coupled to motor proteins and how this transport is regulated to meet changing demand for protein breakdown remains largely unknown. We show that the conserved proteasome-binding protein PI31 serves as an adaptor to directly couple proteasomes with dynein light chain proteins (DYNLL1/2). Inactivation of PI31 inhibits proteasome motility in axons and disrupts synaptic protein homeostasis, structure and function. Moreover, phosphorylation of PI31 at a conserved site by p38 MAP kinase promotes binding to DYNLL1/2, and a non-phosphorable PI31 mutant impairs proteasome movement in axons, suggesting a mechanism to regulate loading of proteasomes onto motor proteins. Because mutations affecting PI31 activity are associated with human neurodegenerative diseases, impairment of PI31-mediated axonal transport of proteasomes may be the root cause of these disorders.

scholarly journals Temperature-Dependent Activity of Motor Proteins: Energetics and Their Implications for Collective Behavior

2021 ◽  
Vol 9 ◽  
Author(s):  
Saumya Yadav ◽  
Ambarish Kunwar
Keyword(s):  
Single Molecule ◽  
Molecular Motors ◽  
Intracellular Transport ◽  
Motor Proteins ◽  
Atp Hydrolysis ◽  
Molecular Motor ◽  
Surrounding Medium ◽  
Biochemical Properties ◽  
Cellular Transport ◽  
Temperature Dependent

Molecular motor proteins are an extremely important component of the cellular transport system that harness chemical energy derived from ATP hydrolysis to carry out directed mechanical motion inside the cells. Transport properties of these motors such as processivity, velocity, and their load dependence have been well established through single-molecule experiments. Temperature dependent biophysical properties of molecular motors are now being probed using single-molecule experiments. Additionally, the temperature dependent biochemical properties of motors (ATPase activity) are probed to understand the underlying mechanisms and their possible implications on the enzymatic activity of motor proteins. These experiments in turn have revealed their activation energies and how they compare with the thermal energy available from the surrounding medium. In this review, we summarize such temperature dependent biophysical and biochemical properties of linear and rotary motor proteins and their implications for collective function during intracellular transport and cellular movement, respectively.

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