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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)

Recent new information regarding the proteins required for proper distribution of chromosomes in meiosis has come from studies of Drosophila mutants. These studies reveal that proteins related to the microtubule motor protein, kinesin, function in meiotic chromosome segregation in Drosophila females. The two proteins identified thus far are likely to play very different roles in the process. The ncd protein is a spindle motor in meiosis but may perform a different role in the early mitotic divisions of the embryo. nod functions earlier in meiosis than ncd, prior to the meiotic divisions, and may be either chromosome or spindle associated. The identification of nod as a kinesin protein raises new questions regarding the distributive model of meiotic chromosome segregation.
Chromosoma 1992 Dec
PMID:Meiotic chromosome distribution in Drosophila oocytes: roles of two kinesin-related proteins. 129 Dec 24

We have developed a new model system for studying spindle elongation in vitro using the pennate, marine diatom Cylindrotheca fusiformis. C. fusiformis can be grown in bulk to high densities while in log phase growth and synchronized by a simple light/dark regime. Isolated spindles can be attained in quantities sufficient for biochemical analysis and spindle tubulin is approximately 5% of the total protein present. The spindle isolation procedure results in a 10-fold enrichment of diatom tubulin and a calculated 40-fold increase in spindle protein. Isolated spindles or spindles in permeabilized cells can elongate in vitro by the same mechanism and with the same pharmacological sensitivities as described for other anaphase B models (Cande and McDonald, 1986; Masuda et al., 1990). Using this model, in vitro spindle elongation rate profiles were developed for a battery of nucleotide triphosphates and ATP analogs. The relative rates of spindle elongation produced by various nucleotide triphosphates parallel relative rates seen for kinesin-based motility in microtubule gliding assays. Likewise ATP analogs that allow discrimination between myosin-, dynein-, and kinesin-mediated motility produce relative spindle elongation rates characteristic of kinesin motility. Also, isolated spindle fractions are enriched for a kinesin related protein as identified by a peptide antibody against a conserved region of the kinesin superfamily. These data suggest that kinesin-like motility contributes to spindle elongation during anaphase B of mitosis.
J Cell Biol 1992 Dec
PMID:Physiological evidence for involvement of a kinesin-related protein during anaphase spindle elongation in diatom central spindles. 144 2

In neuronal axons, various kinds of membranous components are transported along microtubules bidirectionally. However, only two kinds of mechanochemical motor proteins, kinesin and brain dynein, had been identified as transporters of membranous organelles in mammalian neurons. Recently, a series of genes that encode proteins closely related to kinesin heavy chain were identified in several organisms including Schizosaccharomyces pombe, Aspergillus niddulans, Saccharomyces cerevisiae, Caenorhabditus elegans, and Drosophila. Most of these members of the kinesin family are implicated in mechanisms of mitosis or meiosis. To address the mechanism of intracellular organelle transport at a molecular level, we have cloned and characterized five different members (KIF1-5), that encode the microtubule-associated motor domain homologous to kinesin heavy chain, in murine brain tissue. Homology analysis of amino acid sequence indicated that KIF1 and KIF5 are murine counterparts of unc104 and kinesin heavy chain, respectively, while KIF2, KIF3, and KIF4 are as yet unidentified new species. Complete amino acid sequence of KIF3 revealed that KIF3 consists of NH2-terminal motor domain, central alpha-helical rod domain, and COOH-terminal globular domain. Complete amino acid sequence of KIF2 revealed that KIF2 consists of NH2-terminal globular domain, central motor domain, and COOH-terminal alpha-helical rod domain. This is the first identification of the kinesin-related protein which has its motor domain at the central part in its primary structure. Northern blot analysis revealed that KIF1, KIF3, and KIF5 are expressed almost exclusively in murine brain, whereas KIF2 and KIF4 are expressed in brain as well as in other tissues. All these members of the kinesin family are expressed in the same type of neurons, and thus each one of them may transport its specific organelle in the murine central nervous system.
J Cell Biol 1992 Dec
PMID:Kinesin family in murine central nervous system. 144 3

Kinesin and dynein are motor proteins that move in opposite directions along microtubules. In this study, we examine the consequences of having kinesin and dynein (ciliary outer arm or cytoplasmic) bound to glass surfaces interacting with the same microtubule in vitro. Although one might expect a balance of opposing forces to produce little or no net movement, we find instead that microtubules move unidirectionally for several microns (corresponding to hundreds of ATPase cycles by a motor) but continually switch between kinesin-directed and dynein-directed transport. The velocities in the plus-end (0.2-0.3 microns/s) and minus-end (3.5-4 microns/s) directions were approximately half those produced by kinesin (0.5 microns/s) and ciliary dynein (6.7 microns/s) alone, indicating that the motors not contributing to movement can interact with and impose a drag upon the microtubule. By comparing two dyneins with different duty ratios (percentage of time spent in a strongly bound state during the ATPase cycle) and varying the nucleotide conditions, we show that the microtubule attachment times of the two opposing motors as well as their relative numbers determine which motor predominates in this assay. Together, these findings are consistent with a model in which kinesin-induced movement of a microtubule induces a negative strain in attached dyneins which causes them to dissociate before entering a force-generating state (and vice versa); reversals in the direction of transport may require the temporary dissociation of the transporting motor from the microtubule. The bidirectional movements described here are also remarkably similar to the back-and-forth movements of chromosomes during mitosis and membrane vesicles in fibroblasts. These results suggest that the underlying mechanical properties of motor proteins, at least in part, may be responsible for reversals in microtubule-based transport observed in cells.
J Cell Biol 1992 Dec
PMID:Directional instability of microtubule transport in the presence of kinesin and dynein, two opposite polarity motor proteins. 146 50

The nonclaret disjunctional (ncd) protein is required for normal chromosome distribution in oocytes and early embryos. Mutants of ncd cause frequent nondisjunction and loss of chromosomes, suggesting a role for the protein in spindle function or chromosome movement in meiosis and early mitosis. The ncd protein contains a region of predicted sequence similarity to the microtubule motor protein, kinesin. In vitro motility assays have demonstrated that ncd is a motor that unexpectedly moves toward the minus ends of microtubules, opposite to the direction of kinesin movement. Using antibodies directed against nonconserved regions of the protein, we have localized the ncd motor protein to the meiotic and early mitotic spindle, and to spindles in a mitotically dividing cultured cell line. Its presence in the spindle of meiotic and mitotic cells implies a role for the protein as a spindle motor. The motor may play an essential role in establishing spindle bipolarity in meiosis.
J Cell Sci 1992 Dec
PMID:The Drosophila ncd microtubule motor protein is spindle-associated in meiotic and mitotic cells. 148 85

The cortical pattern mutant broadened cortical domains (bcd) in Tetrahymena thermophila is unable to complete the nuclear events associated with conjugation. bcd x bcd pairs become arrested at the "nuclear exchange" configuration. Genetic analysis reveals that the bcd conjugal block is 100% penetrant, under macronuclear control, and rescueable (a) by outcrossing to a wild-type partner, (b) by administration of a hyperosmotic shock 5 hr after cells are mixed for mating, or (c) by cytoplasmic transfusion from a wild-type donor. Cytological analysis reveals that the conjugal block is primarily the result of failure in pronuclear fusion (karyogamy). bcd pairs also exhibit reduced nuclear exchange efficiency and a failure of macronuclear anlagen formation. The hypothesis is proposed that the bcd+ gene codes for a microtubule-based organelle "motor" similar to kinesin.
Dev Biol 1991 Dec
PMID:Conjugal blocks in Tetrahymena pattern mutants and their cytoplasmic rescue. I. Broadened cortical domains (bcd). 174 92

Synapsin I plays an important role in the regulation of neurotransmitter release, since it binds to synaptic vesicles and to the cytoskeleton, and it bundles F-actin and microtubules. We have previously shown by tryptic digestion of synapsin I that a 44 kDa fragment contains a binding site for polymerized tubulin. In the present experiments, we test whether synapsin I and microtubule-associated proteins (MAPs) have the same or a different binding site on tubulin molecules. Our results show that heat stable MAPs do not compete with synapsin I for binding to taxol tubulin. In addition, subtilisin digestion of tubulin, which suppresses MAPs binding, does not abolish synapsin I cosedimentation with taxol tubulin. Thus, our results strongly suggest that synapsin I (as reported for kinesin) does not bind to the 4 kDa subtilisin digested C-terminal part of the tubulin molecule.
Biochem Int 1990 Dec
PMID:Do synapsin I and microtubule-associated proteins bind to a common site on polymerized tubulin? 212 53

Kinesin is a microtubule-activated ATPase that moves objects toward the plus end of microtubules and makes microtubules glide along a glass surface. Here we investigate a remarkable effect of the nonhydrolyzable analogue of ATP, adenosine 5'-[beta,gamma-imido]triphosphate (p[NH]ppA), on kinesin-driven microtubule gliding. Microtubule gliding that has been blocked by rapid replacement of ATP with p[NH]ppA requires 1-2 min of exposure to ATP before microtubule gliding resumes. This latency is not shortened by prolonged washing of p[NH]ppA-blocked microtubules in nucleotide-free buffer for up to 15 min, suggesting that ATP binding to a second nucleotide binding site on kinesin triggers the release of bound p[NH]ppA. To test this hypothesis, the release of [3H]p[NH]ppA from kinesin-microtubule complexes was followed in parallel biochemical assays. In nucleotide-free buffer, the bound p[NH]ppA was released over several hours from the complexes. However, addition of ATP caused the release of p[NH]ppA from the kinesin-microtubule complexes within 2 min, which was similar to the latent period for start-up of microtubule gliding after p[NH]ppA inhibition. The stoichiometry of p[NH]ppA bound per kinesin heavy chain at saturation was estimated to be approximately 1:2. These results suggest a model in which each molecule of kinesin has at least two nucleotide binding sites that alternately bind nucleotide.
Proc Natl Acad Sci U S A 1990 Dec
PMID:Delayed start-up of kinesin-driven microtubule gliding following inhibition by adenosine 5'-[beta,gamma-imido]triphosphate. 214 8

The Drosophila ncd gene is required for chromosome segregation during female meiosis. Previous analyses suggested that the ncd gene encoded a protein with sequence similarity to the kinesin motor domain, which suggested that, like kinesin, the ncd protein might be a plus end-directed microtubule motor. Here we describe the expression of ncd protein in E. coli and the initial characterization of the ncd protein's motor properties. The ncd protein is indeed a microtubule motor, but the polarity of movement is minus end directed. The ncd protein also has microtubule bundling activity. These findings limit possible models for the in vivo functions of the ncd protein and suggest that motor proteins with similar sequence can generate movement in opposite directions along a microtubule.
Cell 1990 Dec 21
PMID:The kinesin-like ncd protein of Drosophila is a minus end-directed microtubule motor. 226 38

Single microtubules from squid axoplasm support bidirectional movement of organelles. We previously purified a microtubule translocator (kinesin) that moves latex beads in only one direction along microtubules. In this study, a polar array of microtubules assembled off of centrosomes in vitro was used to demonstrate that kinesin moves latex beads from the minus to the plus ends of microtubules, a direction that corresponds to anterograde transport in the axon. A crude solubilized fraction from squid axoplasm (S1a), however, generates bidirectional movement of beads along microtubules. Retrograde bead movement (1.4 micron/sec) is inhibited by N-ethylmaleimide and 20 microM vanadate while anterograde movement (0.6 micron/sec) is unaffected by these agents. Furthermore, a monoclonal antibody against kinesin, when coupled to Sepharose, removes the anterograde, but not the retrograde, bead translocator from S1a. These results indicate that there is a retrograde bead translocator which is pharmacologically and immunologically distinct from kinesin.
Cell 1985 Dec
PMID:Different axoplasmic proteins generate movement in opposite directions along microtubules in vitro. 241 67


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