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)

The cytoskeleton is involved in several cellular activities, including internalization and transport of foreign particles. Although particular functions to each cytoskeleton component have been described, interactions between those components seem to occur. The involvement of the different host cell cytoskeletal components in uptake and development of Chlamydophila psittaci is incompletely understood. In this study, the participation of the microfilament network along with the kinesin and dynein microtubule motor proteins in the internalization and further development of Chlamydophila psittaci were investigated in L929 fibroblast and BGM epithelial cells. Cytochalasin D disruption of actin filaments, and blockage of the motor proteins through the introduction of monoclonal antibodies into the host cells were carried out, either single or combined, at different moments around bacterial inoculation, and Chlamydophila infectivity determined 24 h post- inoculation by direct immunofluorescence. Our results show that, although Chlamydophila Ipsittaci can make use of both microfilament-dependent and independent entry pathways in both cell types, Chlamydophila internalization and development in the fibroblast cells mainly concerned processes mediated by microfilaments while in the epithelial cells mechanisms that require microtubule motor proteins were the ones predominantly involved. Evidence that mutual participation of the actin and tubulin networks in both host cells are required for optimal growth of Chlamydophila psittaci is also presented.
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PMID:Optimal development of Chlamydophila psittaci in L929 fibroblast and BGM epithelial cells requires the participation of microfilaments and microtubule-motor proteins. 1083 69

The movement of pollen tube organelles relies on cytoskeletal elements. Although the movement of organelles along actin filaments in the pollen tube has been studied widely and is becoming progressively clear, it remains unclear what role microtubules play. Many uncertainties about the role of microtubules in the active transport of pollen tube organelles and/or in the control of this process remain to be resolved. In an effort to determine if organelles are capable of moving along microtubules in the absence of actin, we extracted organelles from tobacco pollen tubes and analyzed their ability to move along in vitro-polymerized microtubules under different experimental conditions. Regardless of their size, the organelles moved at different rates along microtubules in the presence of ATP. Cytochalasin D did not inhibit organelle movement, indicating that actin filaments are not required for organelle transport in our assay. The movement of organelles was cytosol independent, which suggests that soluble factors are not necessary for the organelle movement to occur and that microtubule-based motor proteins are present on the organelle surface. By washing organelles with KI, it was possible to release proteins capable of gliding carboxylated beads along microtubules. Several membrane fractions, which were separated by Suc density gradient centrifugation, showed microtubule-based movement. Proteins were extracted by KI treatment from the most active organelle fraction and then analyzed with an ATP-sensitive microtubule binding assay. Proteins isolated by the selective binding to microtubules were tested for the ability to glide microtubules in the in vitro motility assay, for the presence of microtubule-stimulated ATPase activity, and for cross-reactivity with anti-kinesin antibodies. We identified and characterized a 105-kD organelle-associated motor protein that is functionally, biochemically, and immunologically related to kinesin. This work provides clear evidence that the movement of pollen tube organelles is not just actin based; rather, they show a microtubule-based motion as well. This unexpected finding suggests new insights into the use of pollen tube microtubules, which could be used for short-range transport, as actin filaments are in animal cells.
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PMID:In vitro assays demonstrate that pollen tube organelles use kinesin-related motor proteins to move along microtubules. 1250 35