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)

Previous studies have shown that microtubule-based organelle transport requires a membrane receptor but no kinesin-binding membrane proteins have been isolated. Chick embryo brain microsomes have kinesin bound to their surface, and after detergent solubilization, a matrix with an antibody to the kinesin head domain (SUK-4) (Ingold et al., 1988) bound the solubilized kinesin and retained an equal amount of a microsome protein of 160-kD. Similarly, velocity sedimentation of solubilized membranes showed that kinesin and the 160-kD polypeptide cosedimented at 13S. After alkaline treatment to remove kinesin from the microsomes, the same 160-kD polypeptide doublet bound to a kinesin affinity resin and not to other proteins tested. Biochemical characterization localized this protein to the cytoplasmic face of brain microsomes and indicated that it was an integral membrane protein since it was resistant to alkaline washing. mAbs raised to chick 160-kD protein demonstrated that it was absent in the supernatant and concentrated in the dense microsome fraction. The dense microsome fraction also had the greatest amount of microtubule-dependent motility. With immunofluorescence, the antibodies labeled the ER in chick embryo fibroblasts (similar to the pattern of bound kinesin staining in the same cells) (Hollenbeck, P. J. 1989. J. Cell Biol. 108:2335-2342), astroglia, Schwann cells and dorsal root ganglion cells but staining was much less in the Golgi regions of these cells. Because this protein is a major kinesin-binding protein of motile vesicles and would be expected to bind kinesin to the organelle membrane, we have chosen the name, kinectin, for this protein.
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PMID:Kinectin, a major kinesin-binding protein on ER. 151 92

New molecular motors associated with microtubules and actin have been uncovered very recently. Furthermore, studies of the mechanisms of bidirectional fast axonal transports have clarified new aspects of these processes, such as identification of a kinesin binding protein (kinectin) and regulation of kinesin dissociation from membranous organelles by phosphorylation. These will lead to a more precise understanding of the mechanisms of axonal transports. Concerning the mechanism of the slow transport of cytoskeletal proteins, new approaches have provided further evidence that the axonal cytoskeleton in mammalian systems is largely stationary while dynamic exchanges occur between polymer and a small pool of moving subunits.
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PMID:Mechanism of axonal transport. Identification of new molecular motors and regulations of transports. 751 Aug 57

We have identified a human cDNA that is homologous to the chicken kinectin, a putative receptor for the organelle motor kinesin. The human cDNA clone hybridized to a single 4.6-kb mRNA species that codes for a protein of 156 kDa molecular mass. The predicted primary translation product contains an N-terminal transmembrane helix followed by a bipartite nuclear localization sequence and two further C-terminal leucine zipper motifs. In addition, the aminoacid sequence revealed a large region (327-1362) of predicted alpha-helical coiled coils. A monoclonal antibody CT-1 raised against a GST-kinectin fusion protein produced a perinuclear, endoplasmic reticulum-like staining pattern in diverse cell types from different species, indicating evolutionary conservation. Monoclonal antibody CT-1 and anti-chicken kinectin antibodies cross-reacted both in Western blotting and immunoprecipitation with a 160-kDa protein, confirming the antigenic identity of this 160-kDa protein with chicken kinectin. Epitope tagging studies revealed that the nuclear localization sequence motif of kinectin is not functional. Furthermore, a truncated kinesin cDNA lacking the N-terminal hydrophobic domain revealed a nonspecific cytoplasmic staining pattern. Together the data suggest that kinectin is an integral membrane protein anchored in the endoplasmic reticulum via a transmembrane domain.
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PMID:Molecular cloning and characterization of human kinectin. 778 43

Kinectin is a kinesin-binding protein (Toyoshima et al., 1992) that is required for kinesin-based motility (Kumar et al., 1995). A kinectin cDNA clone containing a 4.7-kilobase insert was isolated from an embryonic chick brain cDNA library by immunoscreening with a panel of monoclonal antibodies. The cDNA contained an open reading frame of 1364 amino acids encoding a protein of 156 kDa. A bacterially expressed product of the full length cDNA bound purified kinesin. Transient expression in CV-1 cells gave an endoplasmic reticulum distribution that depended upon the N-terminal domain. Analysis of the predicted amino acid sequence indicated a highly hydrophobic near N-terminal stretch of 28 amino acids and a large portion (326-1248) of predicted alpha helical coiled coils. The 30-kDa fragment containing the N-terminal hydrophobic region was produced by cell-free in vitro translation and found to assemble with canine pancreas rough microsomes. Cleavage of the N terminus was not observed confirming its role as a potential transmembrane domain. Thus, the kinectin cDNA encodes a cytoplasmic-oriented integral membrane protein that binds kinesin and is likely to be a coiled-coil dimer.
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PMID:Characterization of kinectin, a kinesin-binding protein: primary sequence and N-terminal topogenic signal analysis. 778 44

The motor protein kinesin is implicated in organelle movement toward the plus ends of microtubules, but little is known about its interaction with organelle membranes or about the physiological role of the phosphorylation of kinesin and its associated protein kinectin seen in neurons in vivo (Hollenbeck, P. J. (1993) J. Neurochem. 60, 2265-2275). Here we have demonstrated that the kinesin heavy chain (KHC), light chain, and kinectin isolated from chick brain or sympathetic neurons exist in several isoelectric forms. Metabolic labeling followed by phosphatase treatment showed that these are phosphoisoforms, and that phosphorylation is reversible in vitro. To assess the capability of phosphorylation to regulate kinesin's state and/or activity, we performed 32P and 35S pulse-chase experiments with neuronal cultures and determined that kinesin-associated phosphate turns over 3-4 times faster than the proteins themselves. When the phosphoisoform distributions for different kinesin pools were analyzed, it was found that membrane-associated KHC contained predominantly the most highly phosphorylated isoform, while soluble kinesin consisted of less phosphorylated KHC isoforms. Nerve growth factor-induced neurite outgrowth in PC12 cells was found to increase significantly kinesin's 32P specific activity while doubling the relative abundance of the most highly phosphorylated KHC isoform. These results demonstrate that the phosphorylation state of kinesin is closely coupled to its organelle binding and to the magnitude of organelle transport in the cell. We propose that the phosphorylation state of kinesin and associated proteins may regulate motility via association with organelle membranes and, specifically, that KHC phosphorylation induces membrane association.
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PMID:Phosphorylation of kinesin in vivo correlates with organelle association and neurite outgrowth. 789 Jun 79

The membrane anchor for the molecular motor kinesin is a critical site involved in intracellular membrane trafficking. Monoclonal antibodies specific for the cytoplasmic surface of chick brain microsomes were used to define proteins involved in microtubule-dependent transport. One of four antibodies tested inhibited plus-end-directed vesicle motility by approximately 90 percent even as a monovalent Fab fragment and reduced kinesin binding to vesicles. This antibody bound to the cytoplasmic domain of kinectin, an integral membrane protein of the endoplasmic reticulum that binds to kinesin. Thus, kinectin acted as a membrane anchor protein for kinesin-driven vesicle motility.
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PMID:Kinectin, an essential anchor for kinesin-driven vesicle motility. 789 10

Great advances in the field of axonal transport have been made in the past year, including the identification of new molecular motors associated with microtubules and actin. In addition, studies on the mechanisms of bidirectional fast axonal transport have clarified new aspects of this process, such as the isolation of a kinesin-binding protein, kinectin, and the finding that phosphorylation regulates kinesin's dissociation from membranous organelles. New approaches to studying slow transport of cytoskeletal proteins have provided further evidence that the axonal cytoskeleton in mammalian systems is largely stationary, although a dynamic exchange occurs between polymers and a small pool of moving subunits.
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PMID:Axonal transport and the cytoskeleton. 826 Aug 21

The microtubule-based motor protein kinesin is thought to drive anterograde organelle transport in axons, but nothing is known about how its force-generating activity or organelle-binding properties are regulated. Studies in other motility systems suggest that protein phosphorylation is a reasonable candidate for this function. I report here that the kinesin heavy chain (HC) and light chain (LC), as well as the 160-kDa kinesin-associated protein kinectin, are phosphorylated in vivo in cultures of chick sympathetic neurons and PC12 cells labeled metabolically with 32P. In neurons, both kinesin chains are phosphorylated exclusively on serine residues, and limiting tryptic digestion demonstrated that the phosphorylation sites are clustered in a region of < or = 5 kDa for the HC and < or = 14 kDa for the LC. Partial tryptic digestion of 32P-labeled HC followed by immunoblotting with SUK4 monoclonal anti-HC and fluorography showed that the sites of HC phosphorylation are outside the globular N-terminal head region where kinesin's microtubule-binding and mechanochemical activities reside. Treatment of metabolically labeled neurons with forskolin, phorbol esters, or calcium ionophore did not alter the extent of phosphorylation, the phosphoamino acid composition, or the V8 protease phosphopeptide maps of the HC, LC, and 160-kDa protein, with one exception: treatment with calcium ionophore reduced the specific activity of the LC. In addition, when kinesin from PC12 cells was compared with that from PC12-derived cell lines lacking protein kinase A activity, neither the extent of phosphorylation nor the phosphopeptide maps were altered for either chain. Phosphopeptide mapping experiments also showed that postlysis kinase activity can phosphorylate both the neuronal HC and LC at sites not phosphorylated in vivo.
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PMID:Phosphorylation of neuronal kinesin heavy and light chains in vivo. 849 30

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

Kinectin, a major kinesin receptor on endoplasmic reticulum, was visualized with anti-kinectin monoclonal antibodies (mAbs) in the adult chicken nervous system in comparison with kinesin immunostaining. Anti-kinectin mAbs punctately stained cell bodies and proximal dendrites of motor neurons in spinal cords. Axons of motor neurons were not stained with anti-kinectin mAbs, but stained heavily with anti-kinesin mAbs. This suggest that the kinesin receptor responsible for kinesin-driven anterograde fast axonal transport is different from kinectin. Anti-kinectin mAbs strongly stained neuronal cell bodies in spinal ganglion, nuclei in brainstem, cerebellar nuclei, striatum and cerebral cortex. Small neurons in cerebellar cortex and optic lobe showed relatively weak reaction, suggesting that the amount of kinectin correlates with the size of neuronal cell bodies.
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PMID:Kinectin distribution in chicken nervous system. 881 68


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