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)

The Rho family small G proteins are implicated in various cell functions, such as cell morphological change, cell motility, and cytokinesis. However, their modes of action in regulating these cell functions remain to be clarified. In the present study, we have isolated a cDNA encoding a protein which interacts with the GTP-bound form, but not with the GDP-bound form, of the Rho family members, including RhoA, Racl, and Cdc42, by the yeast two-hybrid method. This protein is kinectin, known to be a vesicle membrane anchoring protein of kinesin, which is an ATPase motor transporting vesicles along microtubules.
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PMID:Interaction of the Rho family small G proteins with kinectin, an anchoring protein of kinesin motor. 876 96

Smg GDS is a regulator having two activities on a group of small G proteins including the Rho and Rap1 family members and Ki-Ras; one is to stimulate their GDP/GTP exchange reactions, and the other is to inhibit their interactions with membranes. Structurally, it has 11 Arm repeats, a protein interaction motif, found in the Drosophila Armadillo protein, a homolog of mammalian beta-catenin. We have isolated here an Smg GDS-interacting protein from a human brain cDNA library by use of the yeast two-hybrid method and named it SMAP (Smg GDS-associated protein). SMAP was a protein with a Mr of 91,189 and 792 amino acids. SMAP had 9 Arm repeats. Recombinant SMAP interacted with recombinant Smg GDS but did not affect the two activities of Smg GDS on RhoA. SMAP was tyrosine phosphorylated by v-Src, and this phosphorylation reduced the affinity of SMAP for Smg GDS. Tissue and subcellular distribution analyses indicated that SMAP was ubiquitously expressed and highly concentrated at the endoplasmic reticulum area. Searches for sequence homology to SMAP revealed that SMAP was significantly homologous to sea urchin SpKAP115, suggesting that SMAP is a mammalian counterpart of SpKAP115 or its related protein. SpKAP115 is an accessory subunit of sea urchin kinesin II, an ATPase motor that transports vesicles along microtubules. These results suggest that SMAP serves as an adaptor for both Smg GDS and kinesin II or its related protein and links them with both the Smg GDS-regulated small G protein and Src tyrosine kinase signalings.
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PMID:SMAP, an Smg GDS-associating protein having arm repeats and phosphorylated by Src tyrosine kinase. 890 Jan 89

The band 4.1 domain was first identified in the red blood cell protein band 4.1, and subsequently in ezrin, radixin, and moesin (ERM proteins) and other proteins, including tumor suppressor merlin/schwannomin, talin, unconventional myosins VIIa and X, and protein tyrosine phosphatases. Recently, the presence of a structurally related domain has been demonstrated in the N-terminal region of two groups of tyrosine kinases: the focal adhesion kinases (FAK) and the Janus kinases (JAK). Additional proteins containing the 4.1/JEF (JAK, ERM, FAK) domain include plant kinesin-like calmodulin-binding proteins (KCBP) and a number of uncharacterized open reading frames identified by systematic DNA sequencing. Phylogenetic analysis of amino acid sequences suggests that band 4.1/JEF domains can be grouped in several families that have probably diverged early during evolution. Hydrophobic cluster analysis indicates that the band 4.1/JEF domains might consist of a duplicated module of approximately 140 residues and a central hinge region. A conserved property of the domain is its capacity to bind to the membrane-proximal region of the C-terminal cytoplasmic tail of proteins with a single transmembrane segment. Many proteins with band 4.1/JEF domains undergo regulated intra- or intermolecular homotypic interactions. Additional properties common to band 4.1/JEF domains of several proteins are binding of phosphoinositides and regulation by GTPases of the Rho family. Many proteins with band 4. 1/JEF domains are associated with the actin-based cytoskeleton and are enriched at points of contact with other cells or the extracellular matrix, from which they can exert control over cell growth. Thus, proteins with band 4.1/JEF domain are at the crossroads between cytoskeletal organization and signal transduction in multicellular organisms. Their importance is underlined by the variety of diseases that can result from their mutations.
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PMID:Janus kinases and focal adhesion kinases play in the 4.1 band: a superfamily of band 4.1 domains important for cell structure and signal transduction. 999 Aug 61

The RHO1 gene encodes a yeast homolog of the mammalian RhoA protein. Rho1p is localized to the growth sites and is required for bud formation. We have recently shown that Bni1p is one of the potential downstream target molecules of Rho1p. The BNI1 gene is implicated in cytokinesis and the establishment of cell polarity in Saccharomyces cerevisiae but is not essential for cell viability. In this study, we screened for mutations that were synthetically lethal in combination with a bni1 mutation and isolated two genes. They were the previously identified PAC1 and NIP100 genes, both of which are implicated in nuclear migration in S. cerevisiae. Pac1p is a homolog of human LIS1, which is required for brain development, whereas Nip100p is a homolog of rat p150(Glued), a component of the dynein-activated dynactin complex. Disruption of BNI1 in either the pac1 or nip100 mutant resulted in an enhanced defect in nuclear migration, leading to the formation of binucleate mother cells. The arp1 bni1 mutant showed a synthetic lethal phenotype while the cin8 bni1 mutant did not, suggesting that Bni1p functions in a kinesin pathway but not in the dynein pathway. Cells of the pac1 bni1 and nip100 bni1 mutants exhibited a random distribution of cortical actin patches. Cells of the pac1 act1-4 mutant showed temperature-sensitive growth and a nuclear migration defect. These results indicate that Bni1p regulates microtubule-dependent nuclear migration through the actin cytoskeleton. Bni1p lacking the Rho-binding region did not suppress the pac1 bni1 growth defect, suggesting a requirement for the Rho1p-Bni1p interaction in microtubule function.
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PMID:Bni1p regulates microtubule-dependent nuclear migration through the actin cytoskeleton in Saccharomyces cerevisiae. 1056 27

RhoG is a member of the Rho family of GTPases that activates Rac1 and Cdc42 through a microtubule-dependent pathway. To gain understanding of RhoG downstream signaling, we performed a yeast two-hybrid screen from which we identified kinectin, a 156-kDa protein that binds in vitro to conventional kinesin and enhances microtubule-dependent kinesin ATPase activity. We show that RhoG(GTP) specifically interacts with the central domain of kinectin, which also contains a RhoA binding domain in its C terminus. Interaction was confirmed by coprecipitation of kinectin with active RhoG(G12V) in COS-7 cells. RhoG, kinectin, and kinesin colocalize in REF-52 and COS-7 cells, mainly in the endoplasmic reticulum but also in lysosomes. Kinectin distribution in REF-52 cells is modulated according to endogenous RhoG activity. In addition, by using injection of anti-kinectin antibodies that challenge RhoG-kinectin interaction or by blocking anti-kinesin antibodies, we show that RhoG morphogenic activity relies on kinectin interaction and kinesin activity. Finally, kinectin overexpression elicits Rac1- and Cdc42-dependent cytoskeletal effects and switches cells to a RhoA phenotype when RhoG activity is inhibited or microtubules are disrupted. The functional links among RhoG, kinectin, and kinesin are further supported by time-lapse videomicroscopy of COS-7 cells, which showed that the microtubule-dependent lysosomal transport is facilitated by RhoG activation or kinectin overexpression and is severely stemmed upon RhoG inhibition. These data establish that kinectin is a key mediator of microtubule-dependent RhoG activity and suggest that kinectin also mediates RhoG- and RhoA-dependent antagonistic pathways.
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PMID:Kinectin is a key effector of RhoG microtubule-dependent cellular activity. 1168 93

p120 catenin (p120) is a component of adherens junctions and has been implicated in regulating cadherin-based cell adhesion as well as the activity of Rho small GTPases, but its exact roles in cell-cell adhesion are unclear. Using time-lapse imaging, we show that p120-GFP associates with vesicles and exhibits unidirectional movements along microtubules. Furthermore, p120 forms a complex with kinesin heavy chain through the p120 NH2-terminal head domain. Overexpression of p120, but not an NH2-terminal deletion mutant deficient in kinesin binding, recruits endogenous kinesin to N-cadherin. Disruption of the interaction between N-cadherin and p120, or the interaction between p120 and kinesin, leads to a delayed accumulation of N-cadherin at cell-cell contacts during calcium-initiated junction reassembly. Our analyses identify a novel role of p120 in promoting cell surface trafficking of cadherins via association and recruitment of kinesin.
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PMID:p120 catenin associates with kinesin and facilitates the transport of cadherin-catenin complexes to intercellular junctions. 1461 49

p120-catenin exists in a membrane-associated cadherin-bound pool, a cytosolic pool that affects Rho GTPases, and a nuclear pool that is thought to associate with the methylation-relevant transcriptional repressor Kaiso. We show here that cytoplasmic p120 can also associate both directly and indirectly with the microtubule network, and that p120 traffics along microtubules toward their plus ends. The direct binding required most of the armadillo repeats and was mutually exclusive for interaction with E-cadherin. Perturbing the p120-microtubule interaction with nocodazole or taxol markedly affected both the tubulin interaction and the balance between cytoplasmic and nuclear p120. The indirect binding occurred via a novel interaction between a segment of the p120 N-terminal domain and conventional kinesin heavy chains. Selective uncoupling of the p120-kinesin interaction by overexpression of the respective p120 and kinesin-binding fragments promoted nuclear p120 accumulation. In addition, expression of full-length kinesin reduced the nuclear accumulation of p120 and blocked the branching phenotype associated with p120 overexpression. Taken together, the data suggest that kinesin affects both the targeting and activity of p120 at several cellular locations.
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PMID:A novel interaction between kinesin and p120 modulates p120 localization and function. 1467 16

The bipolar mitotic spindle is responsible for segregating sister chromatids at anaphase. Microtubule motor proteins generate spindle bipolarity and enable the spindle to perform mechanical work. A major change in spindle architecture occurs at anaphase onset when central spindle assembly begins. This structure regulates the initiation of cytokinesis and is essential for its completion. Central spindle assembly requires the centralspindlin complex composed of the Caenorhabditis elegans ZEN-4 (mammalian orthologue MKLP1) kinesin-like protein and the Rho family GAP CYK-4 (MgcRacGAP). Here we describe a regulatory mechanism that controls the timing of central spindle assembly. The mitotic kinase Cdk1/cyclin B phosphorylates the motor domain of ZEN-4 on a conserved site within a basic amino-terminal extension characteristic of the MKLP1 subfamily. Phosphorylation by Cdk1 diminishes the motor activity of ZEN-4 by reducing its affinity for microtubules. Preventing Cdk1 phosphorylation of ZEN-4/MKLP1 causes enhanced metaphase spindle localization and defects in chromosome segregation. Thus, phosphoregulation of the motor domain of MKLP1 kinesin ensures that central spindle assembly occurs at the appropriate time in the cell cycle and maintains genomic stability.
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PMID:Cell cycle regulation of central spindle assembly. 1531 3

Kinectin is an integral transmembrane protein on the endoplasmic reticulum, binding to kinesin, interacting with Rho GTPase and anchoring the translation elongation factor-1 complex. There has been debate on the specific role(s) of kinectin in different species and cell types. Here we identified 15 novel kinectin isoforms in the mouse nervous system, constituting a family of alternatively spliced carboxyl-terminal variants. Isoform expression is subject to cell type- and developmental stage-specific regulation. We raised specific antibodies to the kinectin variants to characterise their differential intracellular localisation and discovered that certain kinectin isoforms are found in axons where kinectin was previously believed to be absent. We also demonstrated in vivo by overexpression and RNA interference assay that kinectin is selectively involved in the transport of specific types of organelles. A 160 kDa kinectin species is mainly concentrated in the endoplasmic reticulum, anchored via its transmembrane domain and is essential for endoplasmic reticulum membrane extension. A 120 kDa kinectin species is specifically associated with mitochondria, and its interaction with kinesin was found to influence mitochondrial dynamics. These findings contribute to a more unified view of kinectin function. They suggest that different cellular processes use specific kinectin isoforms to mediate intracellular motility and targeting by transient interaction with different motor proteins or other binding partners.
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PMID:Distribution and functions of kinectin isoforms. 1531 74

The correct localization of myosin II to the equatorial cortex is crucial for proper cell division. Here, we examine a collection of genes that cause defects in cytokinesis and reveal with live cell imaging two distinct phases of myosin II localization. Three genes in the rho1 signaling pathway, pebble (a Rho guanidine nucleotide exchange factor), rho1, and rho kinase, are required for the initial recruitment of myosin II to the equatorial cortex. This initial localization mechanism does not require F-actin or the two components of the centralspindlin complex, the mitotic kinesin pavarotti/MKLP1 and racGAP50c/CYK-4. However, F-actin, the centralspindlin complex, formin (diaphanous), and profilin (chickadee) are required to stably maintain myosin II at the furrow. In the absence of these latter genes, myosin II delocalizes from the equatorial cortex and undergoes highly dynamic appearances and disappearances around the entire cell cortex, sometimes associated with abnormal contractions or blebbing. Our findings support a model in which a rho kinase-dependent event, possibly myosin II regulatory light chain phosphorylation, is required for the initial recruitment to the furrow, whereas the assembly of parallel, unbranched actin filaments, generated by formin-mediated actin nucleation, is required for maintaining myosin II exclusively at the equatorial cortex.
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PMID:Distinct pathways control recruitment and maintenance of myosin II at the cleavage furrow during cytokinesis. 1617 42


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