scholarly journals Kinesin-related proteins in the mammalian testes: candidate motors for meiosis and morphogenesis.

1996 ◽  
Vol 7 (2) ◽  
pp. 289-305 ◽  
Author(s):  
A O Sperry ◽  
L P Zhao
Keyword(s):  
Cell Division ◽  
Molecular Motors ◽  
Motor Proteins ◽  
Sequence Similarity ◽  
Tail Domain ◽  
Mitotic Apparatus ◽  
New Members ◽  
Mitotic Motors ◽  
Kinesin Superfamily ◽  
Related Proteins

The kinesin superfamily of molecular motors comprises proteins that participate in a wide variety of motile events within the cell. Members of this family share a highly homologous head domain responsible for force generation attached to a divergent tail domain thought to couple the motor domain to its target cargo. Many kinesin-related proteins (KRPs) participate in spindle morphogenesis and chromosome movement in cell division. Genetic analysis of mitotic KRPs in yeast and Drosophila, as well as biochemical experiments in other species, have suggested models for the function of KRPs in cell division, including both mitosis and meiosis. Although many mitotic KRPs have been identified, the relationship between mitotic motors and meiotic function is not clearly understood. We have used sequence similarity between mitotic KRPs to identify candidates for meiotic and/or mitotic motors in a vertebrate. We have identified a group of kinesin-related proteins from rat testes (termed here testes KRP1 through KRP6) that includes new members of the bimC and KIF2 subfamilies as well as proteins that may define new kinesin subfamilies. Five of the six testes KRPs identified are expressed primarily in testes. Three of these are expressed in a region of the seminiferous epithelia (SE) rich in meiotically active cells. Further characterization of one of these KRPs, KRP2, showed it to be a promising candidate for a motor in meiosis: it is localized to a meiotically active region of the SE and is homologous to motor proteins associated with the mitotic apparatus. Testes-specific genes provide the necessary probes to investigate whether the motor proteins that function in mammalian meiosis overlap with those of mitosis and whether motor proteins exist with functions unique to meiosis. Our search for meiotic motors in a vertebrate testes has successfully identified proteins with properties consistent with those of meiotic motors in addition to uncovering proteins that may function in other unique motile events of the SE.

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 Sequence similarity of mammalian epoxide hydrolases to the bacterial haloalkane dehalogenase and other related proteins

FEBS Letters ◽  
1994 ◽  
Vol 338 (3) ◽  
pp. 251-256 ◽  
Author(s):  
Michael Arand ◽  
David F. Grant ◽  
Jeffrey K. Beetham ◽  
Thomas Friedberg ◽  
Franz Oesch ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Haloalkane Dehalogenase ◽  
Epoxide Hydrolases ◽  
Related Proteins

Asymmetric cell division in fucoid algae: a role for cortical adhesions in alignment of the mitotic apparatus

2001 ◽  
Vol 114 (23) ◽  
pp. 4319-4328
Author(s):  
Sherryl R. Bisgrove ◽  
Darryl L. Kropf
Keyword(s):  
Cell Division ◽  
Asymmetric Cell Division ◽  
Cell Cortex ◽  
Mitotic Apparatus ◽  
Pharmacological Agents ◽  
Division Plane ◽  
Adhesion Sites ◽  
Spindle Poles ◽  
Pelvetia Compressa ◽  
Two Phases

The first cell division in zygotes of the fucoid brown alga Pelvetia compressa is asymmetric and we are interested in the mechanism controlling the alignment of this division. Since the division plane bisects the mitotic apparatus, we investigated the timing and mechanism of spindle alignments. Centrosomes, which give rise to spindle poles, aligned with the growth axis in two phases – a premetaphase rotation of the nucleus and centrosomes followed by a postmetaphase alignment that coincided with the separation of the mitotic spindle poles during anaphase and telophase. The roles of the cytoskeleton and cell cortex in the two phases of alignment were analyzed by treatment with pharmacological agents. Treatments that disrupted cytoskeleton or perturbed cortical adhesions inhibited pre-metaphase alignment and we propose that this rotational alignment is effected by microtubules anchored at cortical adhesion sites. Postmetaphase alignment was not affected by any of the treatments tested, and may be dependent on asymmetric cell morphology.

scholarly journals Parts list for a microtubule depolymerising kinesin

2018 ◽  
Vol 46 (6) ◽  
pp. 1665-1672 ◽  
Author(s):  
Claire T. Friel ◽  
Julie P. Welburn
Keyword(s):  
Chromosome Segregation ◽  
Molecular Motors ◽  
Neuronal Development ◽  
Current Understanding ◽  
Cellular Functions ◽  
Microtubule Cytoskeleton ◽  
Microtubule Binding ◽  
Large Group ◽  
Kinesin Superfamily ◽  
Different Parts

The Kinesin superfamily is a large group of molecular motors that use the turnover of ATP to regulate their interaction with the microtubule cytoskeleton. The coupled relationship between nucleotide turnover and microtubule binding is harnessed in various ways by these motors allowing them to carry out a variety of cellular functions. The Kinesin-13 family is a group of specialist microtubule depolymerising motors. Members of this family use their microtubule destabilising activity to regulate processes such as chromosome segregation, maintenance of cilia and neuronal development. Here, we describe the current understanding of the structure of this family of kinesins and the role different parts of these proteins play in their microtubule depolymerisation activity and in the wider function of this family of kinesins.

scholarly journals A Quantitative Description of Protoplasmic Movement During Cleavage in the Sea-Urchin Egg

1958 ◽  
Vol 35 (2) ◽  
pp. 407-424
Author(s):  
Y. HIRAMOTO
Keyword(s):  
Cell Division ◽  
Sea Urchin ◽  
Quantitative Description ◽  
Motive Force ◽  
Mitotic Apparatus ◽  
Band Theory ◽  
Cytoplasmic Granules ◽  
Carbon Particles ◽  
Sea Urchin Egg ◽  
Protoplasmic Movement

1. Protoplasmic movements during cleavage in the eggs of the heart-urchin Clypeaster japonicus have been followed by tracing the movements of cytoplasmic granules and of carbon particles adhering to the surface. 2. These movements are quantitatively described in normal eggs and in eggs whose mitotic apparatus has been destroyed by colchicine. 3. The results obtained are qualitatively similar to those obtained by Spek and by Dan and his collaborators. 4. Endoplasmic movement and changes in the length and shape of the astral rays are readily explained by the contracting-ring (band) theory. 5. The location of the motive force of cell division is discussed.

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.

Characterization of mitotic motors by their relative sensitivity to AMP-PNP

1989 ◽  
Vol 94 (3) ◽  
pp. 425-441
Author(s):  
G.M. Lee
Keyword(s):  
Fluorescence Intensity ◽  
Molecular Motors ◽  
Lucifer Yellow ◽  
Relative Sensitivity ◽  
Chromosome Movement ◽  
Anaphase Onset ◽  
Mitotic Motors ◽  
Spindle Elongation ◽  
Tubulin Immunofluorescence

The relative sensitivities of the motors for mitotic chromosome movements and saltatory motion were compared using a nonhydrolyzable analog of ATP, AMP-PNP. K+AMP-PNP was microinjected into PtKl cells at the time of nuclear envelope disassembly or at anaphase onset. To produce a dose-response curve for the effect of AMP-PNP on the rate of movement, the intracellular concentration of AMP-PNP in individual cells was measured. The volume injected into each cell was determined by adding dextrans labeled with Lucifer Yellow to the injection buffer, measuring the injected cell's fluorescence intensity, and then comparing the value with the fluorescence intensity of known volumes of Lucifer Yellow dextran solution. AMP-PNP produced a 50% inhibition of spindle elongation at 0.2 mM, of saltatory motion at 0.8 mM, and of chromosome movement at 8.6 mM. Prometaphase chromosome movement and anaphase chromosome-to-pole movement were similarly inhibited by AMP-PNP. Equivalent volumes of injection buffer containing 1% Lucifer Yellow dextran had no effect on chromosome movement, spindle elongation or saltatory motion. Although AMP-PNP occasionally produced shorter anaphase spindles, tubulin immunofluorescence revealed the presence of abundant spindle microtubules. Metaphase cells treated with very high cell concentrations of AMP-PNP had spindles with unusually long astral microtubules; thus microtubules are stabilized rather than broken down by AMP-PNP. In conclusion, spindle elongation is four times more sensitive than saltatory motion to AMP-PNP and 40 times more sensitive than chromosome movement. When these sensitivities to AMP-PNP are considered with the results from other studies, it can be concluded that the molecular motors for spindle elongation, chromosome movement and saltatory motion are different.

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