Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.4.4 (kinesin)
 5,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ultrastructural and functional studies of degranulation responses by human neutrophils have suggested that microtubules (MTs) have a role in the intracellular transport of neutrophil granules. We have found that granule-MT complexes can be isolated from disrupted taxol-treated (1.0 microM) neutrophils, visualized by electron microscopy, and quantified in terms of granules per MT length. After incubation of neutrophils with the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP), granule-MT complex formation was found to be increased two- to threefold. Enhanced binding of granules to MTs was detectable within 30 s of fMLP stimulation and was dependent on the concentration of fMLP. Incubation of cells with dibutyryl cAMP inhibited this fMLP-stimulated granule-MT complex formation in a dose-responsive fashion. These granule-MT interactions could be reproduced in a cell-free system with neutrophil granules isolated by density gradient centrifugation and MTs polymerized from phosphocellulose-purified tubulin. Furthermore, reconstituted granule-MT interactions were found to be modulated by ATPase inhibitors. Sodium orthovanadate increased granule-MT interactions in a concentration-dependent manner, while AMP-PNP, a nonhydrolyzable ATP analogue, and N-ethylmaleimide decreased or eliminated these interactions. In addition, we found that a MT-activated ATPase could be recovered from intact neutrophil granules by salt extraction, and that extracts enriched in this ATPase contained a polypeptide of between 115 and 120 kD which binds ATP and is immunologically related to kinesin. These studies demonstrate that cytoplasmic granules interact with MTs in human neutrophils in a regulated stimulus-responsive manner, and they suggest that such interactions may involve an MT-based, ATPase-dependent, vesicle translocation system as has been demonstrated in other types of cells.
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PMID:Interactions of cytoplasmic granules with microtubules in human neutrophils. 254 7

The neck domain of fungal conventional kinesins displays characteristic properties which are reflected in a specific sequence pattern. The exchange of the strictly conserved Tyr 362, not present in animals, into Lys, Cys or Phe leads to a failure to dimerize. The destabilizing effect is confirmed by a lower coiled-coil propensity of mutant peptides. Whereas the Phe substitution has only a structural effect, the Lys and Cys replacements lead to dramatic kinetic changes. The steady state ATPase is 4- to 7-fold accelerated, which may be due to a faster microtubule-stimulated ADP release rate. These data suggest that an inhibitory effect of the fungal neck domain on the motor core is mediated by direct interaction of the aromatic ring of Tyr 362 with the head, whereas the OH group is essential for dimerization. This is the first demonstration of a direct influence of the kinesin neck region in regulation of the catalytic activity.
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PMID:A conserved tyrosine in the neck of a fungal kinesin regulates the catalytic motor core. 1255 46

Bik1p is the budding yeast counterpart of the CLIP-170 family of microtubule plus-end tracking proteins, which are required for dynein localization at plus ends and dynein-dependent spindle positioning. CLIP-170 proteins make up a CAP-Gly microtubule-binding domain, which sustains their microtubule plus-end tracking behaviour. However, in yeast, Bik1p travels towards plus ends as a cargo of the plus-end-directed kinesin Kip2p. Additionally, Kip2p behaves as a plus-end-tracking protein; hence, it has been proposed that Bik1p might track plus ends principally as a cargo of Kip2p. Here, we examined Bik1p localization in yeast strains expressing mutant tubulin lacking the C-terminal amino acid (Glu tubulin; lacking Phe), the interaction of which with Bik1p is severely impaired compared with wild type. In Glu-tubulin strains, despite the presence of robust Kip2p comets at microtubule plus ends, Bik1p failed to track plus ends. Despite Bik1p depletion at plus ends, dynein positioning at the same plus ends was unperturbed. Video microscopy and genetic evidence indicated that dynein was transported at plus ends in a Kip2p-Bik1p-dependent manner, and was then capable of tracking Bik1p-depleted plus ends. These results indicate that Bik1p interactions with tubulin are important for Bik1p plus-end tracking, and suggest alternative pathways for Bik1p-Kip2p-dependent dynein localization at plus ends.
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PMID:A new role for kinesin-directed transport of Bik1p (CLIP-170) in Saccharomyces cerevisiae. 1841 Dec 45

Mitotic spindle assembly and maintenance relies on kinesin-5 motors that act as bipolar homotetramers to crosslink microtubules. Kinesin-5 motors have been the subject of extensive structure-function analysis, but the regulation of their activity in the context of mitotic progression remains less well understood. We report here that Drosophila kinesin-5 (KLP61F) is regulated by Drosophila Wee1 (dWee1). Wee1 tyrosine kinases are known to regulate mitotic entry via inhibitory phosphorylation of Cdk1. Recently, we showed that dWee1 also plays a role in mitotic spindle positioning through gamma-tubulin and spindle fidelity through an unknown mechanism. Here, we investigated whether a KLP61F-dWee1 interaction could explain the latter role of dWee1. We found that dWee1 phosphorylates KLP61F in vitro on three tyrosines within the head domain, the catalytic region that mediates movement along microtubules. In vivo, KLP61F with tyrosine-->phenylalanine mutations fails to complement a klp61f mutant and dominantly induces spindle defects similar to ones seen in dwee1 mutants. We propose that phosphorylation of the KLP61F catalytic domain by dWee1 is important for the motor's function. This study identifies a second substrate for a Wee1 kinase and provides evidence for phosphoregulation of a kinesin in the head domain.
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PMID:Tyrosines in the kinesin-5 head domain are necessary for phosphorylation by Wee1 and for mitotic spindle integrity. 1980 Feb 37

KIFC1 (HSET), a member of the kinesin-14 family of motor proteins, plays an essential role in centrosomal bundling in cancer cells, but its function is not required for normal diploid cell division. To explore the potential of KIFC1 as a therapeutic target for human cancers, a series of potent KIFC1 inhibitors featuring a phenylalanine scaffold was developed from hits identified through high-throughput screening (HTS). Optimization of the initial hits combined both design-synthesis-test cycles and an integrated high-throughput synthesis and biochemical screening method. An important aspect of this integrated method was the utilization of DMSO stock solutions of compounds registered in the corporate compound collection as synthetic reactants. Using this method, over 1500 compounds selected for structural diversity were quickly assembled in assay-ready 384-well plates and were directly tested after the necessary dilutions. Our efforts led to the discovery of a potent KIFC1 inhibitor, AZ82, which demonstrated the desired centrosome declustering mode of action in cell studies.
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PMID:Discovery of potent KIFC1 inhibitors using a method of integrated high-throughput synthesis and screening. 2545 1