Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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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.
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PMID:Meiotic chromosome distribution in Drosophila oocytes: roles of two kinesin-related proteins. 129 Dec 24

The mechanics of chromosome movement, mitotic spindle assembly and spindle elongation have long been central questions of cell biology. After attachment in prometaphase of a microtubule from one pole, duplicated chromosome pairs travel towards the pole in a rapid but discontinuous motion. This is followed by a slower congression towards the midplate as the chromosome pair orients with each kinetochore attached to the microtubules from the nearest pole. The pairs disjoin at anaphase and translocate to opposite poles and the interpolar distance increases. Here we identify CENP-E as a kinesin-like motor protein (M(r) 312,000) that accumulates in the G2 phase of the cell cycle. CENP-E associates with kinetochores during congression, relocates to the spindle midzone at anaphase, and is quantitatively discarded at the end of the cell division. CENP-E is likely to be one of the motors responsible for mammalian chromosome movement and/or spindle elongation.
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PMID:CENP-E is a putative kinetochore motor that accumulates just before mitosis. 140 65

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.
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PMID:The Drosophila ncd microtubule motor protein is spindle-associated in meiotic and mitotic cells. 148 85

Microtubules are built of tubulin subunits assembled into hollow cylinders which consist of parallel protofilaments. Thus, motor molecules interacting with a microtubule could do so either with one or several tubulin subunits. This makes it difficult to determine the structural requirements for the interaction. One way to approach the problem is to alter the surface lattice. This can be done in several ways. Proto-filaments can be exposed on their inside (C-tubules or "sheets"), they can be made antiparallel (zinc sheets), or they can be rolled up (duplex tubules). We have exploited this polymorphism to study how the motor protein kinesin attached to a glass surface interacts and moves the various tubulin assemblies. Microtubules glide over the surface along straight paths and with uniform velocities. In the case of C-tubules, approximately 40% glide similarly to microtubules, but a major fraction do not glide at all. This indicates (a) that a full cylindrical closure is not necessary for movement, and (b) that the inside surface of microtubules does not support gliding. With zinc sheets, up to 70% of the polymers move, but the movement is discontinuous, has a reduced speed, and follows along a curved path. Since zinc sheets have protofilaments alternating in orientation and polarity, this result suggests that in principle a single protofilament can produce movement, even when its neighbors cannot. Duplex microtubules do not move because they are covered with protofilaments coiled inside out, thus preventing the interaction with kinesin. The data can be explained by assuming that the outside of one protofilament represents the minimal track for kinesin, but smooth gliding requires several parallel protofilaments. Finally, we followed the motion of kinesin-coated microbeads on sea-urchin sperm flagella, from the flagellar outer doublet microtubules to the singlet microtubule tips extending from the A-tubules. No change in behavior was detected during the transition. This indicates that even if these microtubules differ in surface lattice, this does not affect the motility.
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PMID:Tubulin protofilaments and kinesin-dependent motility. 150 Apr 29

The claret (ca) locus in Drosophila encodes a kinesin-related motor molecule that is required for proper distribution of chromosomes in meiosis in females and in the early mitotic divisions of the embryo. Here we demonstrate that a mutant allele of claret non-disjunctional (ca(nd)), non-claret disjunctional Dominant (ncdD), causes abnormalities in meiotic chromosome segregation, but is near wild-type with respect to early mitotic chromosome segregation. DNA sequence analysis of this mutant allele reveals two missense mutations compared with the predicted wild-type protein. One mutation lies in a proposed microtubule binding region of the motor domain and affects an amino acid residue that is conserved in all kinesin-related proteins reported to date. This region of the motor domain can be used to distinguish meiotic and mitotic motor function, defining an amino acid sequence criterion for classifying motors according to function. ncdD's mutant meiotic effect, but near wild-type mitotic effect, suggests that interactions of the ca motor protein with spindle microtubules differ in meiosis and mitosis.
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PMID:Separation of meiotic and mitotic effects of claret non-disjunctional on chromosome segregation in Drosophila. 182 56

The in vivo function of the microtubule motor protein kinesin was examined in Drosophila using genetics and immunolocalization. Kinesin heavy chain mutations (khc) cause abnormal behavior and lethality. Mutant larvae exhibit loss of mobility and tactile responsiveness in the most posterior segments, followed by general paralysis and death during larval or pupal development. Adults homozygous for a temperature-sensitive allele also exhibit a loss in mobility and sensory responses. The data indicate that kinesin function is essential and suggest that kinesin has an important role in the neuromuscular system, perhaps as a motor for axonal transport. The possibility of more general cellular functions remains open, but observation of embryogenesis and morphogenesis in khc mutants suggests that mitosis and the cell cycle can proceed in spite of impaired kinesin function. Immunolocalization suggests that kinesin may have some general cellular functions but that it is not a major component of mitotic spindles.
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PMID:Kinesin heavy chain is essential for viability and neuromuscular functions in Drosophila, but mutants show no defects in mitosis. 182 37

Kinesin was previously immunolocalized to mitotic apparatuses (MAs) of early sea urchin blastomeres (Scholey, J.M., M.E. Porter, P.M. Grissom, and J.R. McIntosh. 1985. Nature [Lond.]. 318:483-486). Here we report evidence that this MA-associated motor protein is a conventional membrane-bound kinesin, rather than a kinesin-like protein. Our evidence includes the observation that the deduced amino acid sequence of this sea urchin kinesin heavy chain is characteristic of a conventional kinesin. In addition, immunolocalizations using antibodies that distinguish kinesin from kinesin-like proteins confirm that conventional kinesin is concentrated in MAs. Finally, our immunocytochemical data further suggest that conventional kinesin is associated with membranes which accumulate in MAs and interphase asters of early sea urchin embryos, and with vesicles that are distributed in the perinuclear region of coelomocytes. Thus kinesin may function as a microtubule-based vesicle motor in some MAs, as well as in the interphase cytoplasm.
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PMID:Subcellular localization and sequence of sea urchin kinesin heavy chain: evidence for its association with membranes in the mitotic apparatus and interphase cytoplasm. 182 46

The 'motor' proteins of eukaryotic cells contain specialized domains that hydrolyse ATP to produce force and movement along a cytoskeletal polymer (actin in the case of the myosin family; microtubules in the case of the kinesin family and dyneins). There are motor-protein superfamilies in which each member has a conserved force-generating domain joined to a different 'tail' which conveys specific attachment properties. The minus-end-directed microtubule motors, the dyneins, may also constitute a superfamily of force-generating proteins with distinct attachment domains. Axonemal outer-arm dynein from sea urchin spermatozoa is a multimeric protein consisting of two heavy chains (alpha and beta) with ATPase activity, three intermediate chains and several light chains. Here I report the sequence of cloned complementary DNA encoding the beta heavy chain of a dynein motor molecule. The predicted amino-acid sequence reveals four ATP-binding consensus sequences in the central domain. The dynein beta heavy chain is thought to associate transiently with a microtubule during ATP hydrolysis, but the ATP-dependent microtubule-binding sequence common to the kinesin superfamily is not found in the dynein beta heavy chain. These unique features distinguish the dynein beta heavy chain from other motor protein superfamilies and may be characteristic of the dynein superfamily.
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PMID:Four ATP-binding sites in the midregion of the beta heavy chain of dynein. 183 Sep 24

The microtubule motor protein kinesin has been conjugated with 5-iodoacetamido fluorescein (5-IAF). The analogue, AF-kinesin, supports organelle motility and the movement of microtubules.
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PMID:Studies using a fluorescent analogue of kinesin. 188 52

Recent evidence has suggested that the principal polypeptide component of the microtubule motor protein kinesin may be a member of an extended superfamily of related motor proteins. To gain insight into how large the kinesin superfamily might be and to begin determining the potential functions in which various superfamily members might participate, we identified and partially characterized six additional members of the Drosophila kinesin superfamily. Genes encoding these proteins were identified by using the polymerase chain reaction with degenerate primers corresponding to highly conserved regions of the kinesin heavy-chain motor domain. Partial sequencing of the six genes revealed that they encode proteins that are 40-60% identical to the motor domain of the kinesin heavy-chain sequence. The cytogenetic locations as well as the developmental and tissue-specific expression patterns have been determined. The data suggest that each of these six kinesin-like proteins may have functions in a wide variety of cell types and tissues.
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PMID:Identification and partial characterization of six members of the kinesin superfamily in Drosophila. 192 6


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