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Query: EC:3.6.4.4 (kinesin)
 5,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To improve our understanding of the roles of microtubule cross-linking motors in mitosis, we analyzed two sea urchin embryonic kinesin-related proteins. It is striking to note that both of these proteins behave as homotetramers, but one behaves as a more compact molecule than the other. These observations suggest that these two presumptive motors could cross-link microtubules into bundles with different spacing. Both motors localize to mitotic spindles, and antibody microinjection experiments suggest that they have mitotic functions. Thus, one of these kinesin-related proteins may cross-link spindle microtubules into loose bundles that are "tightened" by the other.
J Biol Chem 2000 Dec 01
PMID:Roles of two homotetrameric kinesins in sea urchin embryonic cell division. 1100 81

The interplay between microtubules and microtubule-based motors is fundamental to basic aspects of cellular function, such as the intracellular transport of organelles and alterations in cellular morphology during cell locomotion and division. Motor proteins are unique in that they couple nucleotide hydrolysis to force production that can do work. The force transduction by proteins belonging to the kinesin and dynein superfamilies has been thought only to power movement of these motors along the surface of microtubules; however, a growing body of evidence, both genetic and biochemical, suggests that motors can also directly influence the polymerization dynamics of microtubules. For example, at the vertebrate kinetochore, motors interact directly with microtubule ends and modulate polymerization dynamics to orchestrate chromosome movements during mitosis. Although a role for motors in regulating microtubule length has been established, the mechanisms used by motors to promote microtubule growth or shrinkage are unclear, as is an understanding of why cells might choose motors to control dynamics rather than a variety of non-motor proteins known to affect microtubule stability. Elucidation of the exact mechanisms by which motors alter the exchange of tubulin subunits at microtubule ends in vitro may shed light on how microtubule stability is regulated to produce the array of dynamic behavior seen in cells.
J Cell Sci 2000 Dec
PMID:How motor proteins influence microtubule polymerization dynamics. 1108 31

Using pan-kinesin antibodies to screen a differentiating C2C12 cell library, we identified the kinesin proteins KIF3A, KIF3B, and conventional kinesin heavy chain to be present in differentiating skeletal muscle. We compared the expression and subcellular localization characteristics of these kinesins in myogenic cells to others previously identified in muscle, neuronal, and mitotic systems (KIF1C, KIF3C, and mitotic-centromere-associated kinesin). Because members of the KIF3 subfamily of kinesin-related proteins showed altered subcellular fractionation characteristics in differentiating cells, we focused our study of kinesins in muscle on the function of kinesin-II. Kinesin-II is a motor complex comprised of dimerized KIF3A and KIF3B proteins and a tail-associated protein, KAP. The Xenopus homologue of KIF3B, Xklp3, is predominantly localized to the region of the Golgi apparatus, and overexpression of motorless-Xklp3 in Xenopus A6 cells causes mislocalization of Golgi components (). In C2C12 myoblasts and myotubes, KIF3B is diffuse and punctate, and not primarily associated with the Golgi. Overexpression of motorless-KIF3B does not perturb localization of Golgi components in myogenic cells, and myofibrillogenesis is normal. In adult skeletal muscle, KIF3B colocalizes with the excitation-contraction-coupling membranes. We propose that these membranes, consisting of the transverse-tubules and sarcoplasmic reticulum, are dynamic structures in which kinesin-II may function to actively assemble and maintain in myogenic cells.
Mol Biol Cell 2000 Dec
PMID:Expression and partial characterization of kinesin-related proteins in differentiating and adult skeletal muscle. 1110 14

In neurons, neuropeptides and other synaptic components are transported down the axon to the synapse in vesicles using molecular motors of the kinesin family. In the synapse, these neuropeptides are found in dense core vesicles (DCVs), and, following calcium-mediated exocytosis, they interact with receptors on the target cell. We have developed a rapid, large-scale technique for purifying peptide-containing DCVs from specific nuclei in the central nervous system. By using differential velocity gradient and equilibrium gradient centrifugation, neuropeptide-containing DCVs can be separated by size and density from optic nerve (ON) and its termini, the lateral geniculate nuclei and the superior colliculi. Isolated DCVs contain neuropeptides (substance P and brain-derived neurotrophic factor), synaptic vesicle (SV) membrane proteins (SV2, synaptotagmins, synaptophysin, Rab3 and synaptobrevin), SV-associated proteins (alpha-synuclein), secretory markers for DCVs previously isolated (secretogranin II), and beta-amyloid precursor protein. By using electron microscopic techniques, DCV were also visualized and shown to be immunoreactive for neuropeptides, neurotrophins, and SV membrane proteins. Because of the interesting group of physiological and potentially pathophysiological proteins associated with these vesicles; this isolation procedure, applicable to other CNS nuclei, should represent an important research tool.
J Neurosci Res 2000 Dec 15
PMID:Isolation and characterization of substance P-containing dense core vesicles from rabbit optic nerve and termini. 1110 68

By sequence analysis we show that the U104 domain found in the UNC104 subfamily of kinesins is a forkhead homology-associated domain (FHA). A combination of limited proteolysis, mass spectroscopy, and physicochemical analysis define this domain as a genuine autonomously folding domain. Our data show that the FHA domain is shorter than previously reported since the C-terminal alpha-helix is not part of its minimum core. Key amino acids postulated to recognize phosphorylated residues are conserved. These data suggest that the kinesin FHA domains are functional domains involved in protein-protein interactions regulated by phosphorylation.
FEBS Lett 2000 Dec 15
PMID:Kinesin subfamily UNC104 contains a FHA domain: boundaries and physicochemical characterization. 1111 20

Sexual reproduction in the green alga, Chlamydomonas, is regulated by environmental conditions and by cell-cell interactions. After gametogenesis, flagellar adhesion between gametes triggers gamete activation, leading to cell fusion and zygote formation. Recent studies have identified new molecular events that underlie signal transduction during Chlamydomonas fertilization, including expression of a sex-determining protein, phosphorylation of a homeodomain protein, activity of a kinesin II and regulated translocation of an aurora/Ip11-like protein kinase from the cell body to the flagella.
Curr Opin Microbiol 2000 Dec
PMID:Signal transduction during fertilization in the unicellular green alga, Chlamydomonas. 1112 79

The heteromeric kinesins constitute a subfamily of kinesin-related motor complexes that function in several distinct intracellular transport events. The founding member of this subfamily, heterotrimeric kinesin II, has been purified and characterized from early sea urchin embryos, where it was shown using antibody perturbation to be required for the synthesis of motile cilia, presumably by driving the anterograde transport of raft complexes. To further characterize heteromeric kinesin transport pathways, and to attempt to identify cargo molecules, we are using the model organism Caenorhabditis elegans to exploit its well-characterized nervous system and simple genetics. Here we describe methods for large-scale nematode growth and partial purification of kinesin-related holoenzymes from C. elegans, and an in vivo transport assay that allows the direct labeling and visualization of motor complexes and putative cargo molecules moving in living C. elegans neurons. This transport assay is being used to characterize the in vivo transport properties of motor enzymes in living cells, and to exploit a number of existing mutations in C. elegans that may represent constituents of heteromeric kinesin-driven transport pathways, for example, the retrograde intraflagellar transport motor CHE-3 dynein, as well as cargo molecules and/or regulatory molecules.
Methods 2000 Dec
PMID:Analysis of the roles of kinesin and dynein motors in microtubule-based transport in the Caenorhabditis elegans nervous system. 1113 38

Molecular motors are enzymes that couple the energy from nucleoside triphosphate hydrolysis to movement along a filament lattice. The three cytoskeletal motor superfamilies include myosin, dynein, and kinesin. However, in the last decade it has become apparent that the nucleic acid-based enzymes (DNA and RNA polymerases as well as the DNA helicases) share a number of mechanistic features in common with the microtubule and actin motors despite the fact that their cellular functions are so different. This review addresses the mechanistic approaches that have been used to study molecular motors. We discuss the basic biochemical techniques used to characterize a protein preparation, including active site determination and steady-state kinetics. In addition, we present the transient-state kinetic approaches used to define a mechanochemical cycle. We attempt to integrate the information obtained from kinetic studies within the context of motility results to provide a better understanding of the contribution of each approach for dissecting unidirectional force generation.
Methods 2000 Dec
PMID:Kinetics: a tool to study molecular motors. 1113 40

We have previously described the biochemical isolation of 65 kDa and 120 kDa microtubule-associated proteins from carrot cytoskeletons. The 65 kDa MAPs have subsequently been shown to be structural MAPs that reconstitute 30 nm cross-bridges of the kind that maintain cortical microtubules in parallel groups. By exploiting its avid binding to microtubules, we have now devised a method for isolating MAP120 from protoplast extracts, and shown that it has properties of a kinesin-related protein. MAP120 segregates with the cold stable pool of microtubules in carrot cytoskeletons, whilst the 65 kDa MAPs are also associated with the cold-sensitive microtubules. On gradient gels, MAP120 resolves as two kinesin-like bands. We report the isolation of a carrot cDNA, DcKRP120-2, corresponding to a novel kinesin of the BimC class known to move to the plus ends of microtubules. Antibodies raised against specific expressed sequences recognize the upper band, while the lower band is recognized by antibodies to the tobacco kinesin-related protein, TKRP125. We have also isolated a partial genomic carrot DNA, DcKRP120-1, homologous to the motor region of tobacco TKRP125. Immunofluorescence of the two proteins produces different staining patterns. Anti-TKRP125 labels the cortical microtubules and the pre-prophase band, but anti-DcKRP120-2 does so only weakly. Both clearly stain the spindle and the phragmoplast, but in a proportion of cells anti-DcKRP120-2 strongly decorates the phragmoplast mid-line where the plus ends of the microtubules overlap. We discuss the potential roles of these proteins during the microtubule cycle.
Plant J 2000 Dec
PMID:Two kinesin-related proteins associated with the cold-stable cytoskeleton of carrot cells: characterization of a novel kinesin, DcKRP120-2. 1113 19

SIAH-1, a human homologue of the Drosophila seven in absentia (Sina), has been implicated in ubiquitin-mediated proteolysis of different target proteins through its N-terminal RING finger domain. SIAH-1 is also induced during p53-mediated apoptosis. Furthermore, SIAH-1-transfected breast cancer cell line MCF-7 exhibits an altered mitotic process resulting in multinucleated giant cells. Now, using the two-hybrid system, we identified two new SIAH interacting proteins: Kid (kinesin like DNA binding protein) and alpha-tubulin. We demonstrate that SIAH is involved in the degradation of Kid via the ubiquitin-proteasome pathway. Our results suggest that SIAH-1 but not its N-terminal deletion mutant, affects the mitosis by an enhanced reduction of kinesin levels. Our results imply, for the first time, SIAH-1 in regulating the degradation of proteins directly implicated in the mitotic process.
Oncogene 2000 Dec 07
PMID:SIAH-1 interacts with alpha-tubulin and degrades the kinesin Kid by the proteasome pathway during mitosis. 1114 51


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