A 60-kDa plant microtubule-associated protein promotes the growth and stabilization of neurotubules 
            <i>in vitro</i>

Rutten, Twan; Chan, Jordi; Lloyd, Clive

doi:10.1073/pnas.94.9.4469

Cited by 38 publications

(17 citation statements)

References 43 publications

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“…6A). These finding are consistent with the expected stability of axonal microtubules because of microtubule-associated proteins (MAPs) (82)(83)(84)(85). Surprisingly, higher doses of paclitaxel increased the label incorporation into polymers, while slightly decreasing labeling of free tubulin, and reduced the labeling gradient between dimers and polymers.…”

Section: Stable Isotope Incorporation Reveals Effects Of Paclitaxel Osupporting

confidence: 79%

In Vivo Measurement of Microtubule Dynamics Using Stable Isotope Labeling with Heavy Water

Fanara

Turner

Busch

et al. 2004

Journal of Biological Chemistry

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Section: Stable Isotope Incorporation Reveals Effects Of Paclitaxel Osupporting

confidence: 79%

In Vivo Measurement of Microtubule Dynamics Using Stable Isotope Labeling with Heavy Water

Fanara

Turner

Busch

et al. 2004

Journal of Biological Chemistry

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“…Recently, it was determined that MP stabilizes microtubules also upon expression in mammalian cells (33). Modulation of microtubule dynamic instability is a common feature of structural MAPs (83,91,100) and is thought to involve the reduction of interdimer charge-repulsion forces due to binding of MAPs to the microtubule surface (3,20). Thus, it is not surprising that MP-dependent protection against microtubule-disrupting drugs is apparent in cells containing microtubules heavily decorated with MP-GFP.…”

Section: Discussionmentioning

confidence: 99%

Tobacco Mosaic Virus Movement Protein Functions as a Structural Microtubule-Associated Protein

Ashby

Boutant

Seemanpillai

et al. 2006

J Virol

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The cell-to-cell spread of Tobacco mosaic virus infection depends on virus-encoded movement protein (MP), which is believed to form a ribonucleoprotein complex with viral RNA (vRNA) and to participate in the intercellular spread of infectious particles through plasmodesmata. Previous studies in our laboratory have provided evidence that the vRNA movement process is correlated with the ability of the MP to interact with microtubules, although the exact role of this interaction during infection is not known. Here, we have used a variety of in vivo and in vitro assays to determine that the MP functions as a genuine microtubule-associated protein that binds microtubules directly and modulates microtubule stability. We demonstrate that, unlike MP in whole-cell extract, microtubule-associated MP is not ubiquitinated, which strongly argues against the hypothesis that microtubules target the MP for degradation. In addition, we found that MP interferes with kinesin motor activity in vitro, suggesting that microtubule-associated MP may interfere with kinesin-driven transport processes during infection.

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“…In a subsequent study, we were unable to detect bundling with the 60-kDa polypeptide, which we purified by anion exchange chromatography (24). It could have become inactivated, but the possibility has to be considered that MAP65 isoforms differ in their ability to bundle MTs as is known for the neuronal MAP, tau (25).…”

Section: Discussionmentioning

confidence: 99%

The 65-kDa carrot microtubule-associated protein forms regularly arranged filamentous cross-bridges between microtubules

Chan

Jensen

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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In plants, cortical microtubules (MTs) occur in characteristically parallel groups maintained up to one microtubule diameter apart by fine filamentous cross-bridges. However, none of the plant microtubule-associated proteins (MAPs) so far purified accounts for the observed separation between MTs in cells. We previously isolated from carrot cytoskeletons a MAP fraction including 120-and 65-kDa MAPs and have now separated the 65-kDa carrot MAP by sucrose density centrifugation. MAP65 does not induce tubulin polymerization but induces the formation of bundles of parallel MTs in a nucleotide-insensitive manner. The bundling effect is inhibited by porcine MAP2, but, unlike MAP2, MAP65 is heat-labile. In the electron microscope, MAP65 appears as filamentous crossbridges, maintaining an intermicrotubule spacing of 25-30 nm. Microdensitometer-computer correlation analysis reveals that the cross-bridges are regularly spaced, showing a regular axial spacing that is compatible with a symmetrical helical superlattice for 13 protofilament MTs. Because MAP65 maintains in vitro the inter-MT spacing observed in plants and is shown to decorate cortical MTs, it is proposed that this MAP is important for the organization of the cortical array in vivo.A distinctive feature of the cortical array in higher plants is the parallelism of the microtubules (MTs). Electron microscopy (EM) studies show that the array is composed of overlapping MTs that can maintain a parallel relationship over several micrometers (1, 2). Averaged over the entire cell, this degree of order allows the directionality of the entire array to be summarized as ''one cell: one microtubule alignment'' (3) that can be transverse to the cell's long axis or oblique or longitudinal. Immunofluorescence studies show that most cells have organized arrays, with only a few percent being random (3, 4). The factor responsible for this spacing is, therefore, an important element in contributing to the large-scale organization and integrity of the array (5). It is also likely to be involved in channeling the movement of the plasma membranous cellulose synthesizing particles (6).At the EM level, MTs are commonly seen to occur in parallel groups interconnected by filamentous cross-bridges with lengths approximating the diameter of the MTs (1, 2, 7, 8). Several attempts have been made to isolate these filamentous microtubule-associated proteins (MAPs). Cyr and Palevitz (9) found that high speed supernatants from carrot suspension cells caused the bundling of MTs in vitro, with a center-center spacing of 34 nm. A maize MAP fraction containing a range of proteins that also causes MT bundling has been described (10). Jiang et al. (11) showed that a crude cytoplasmic extract from evacuolated tobacco protoplasts bundled MTs with cross-links of two different lengths: 20-25 and 12-15 nm. Later, Jiang and Sonobe (12) used this cytosolic extract to isolate a group of 65-kDa microtubule-associated proteins. Although these proteins induced bundling, they did not form the longer, 20-to 25-nm...

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A 60-kDa plant microtubule-associated protein promotes the growth and stabilization of neurotubules in vitro

Cited by 38 publications

References 43 publications

In Vivo Measurement of Microtubule Dynamics Using Stable Isotope Labeling with Heavy Water

In Vivo Measurement of Microtubule Dynamics Using Stable Isotope Labeling with Heavy Water

Tobacco Mosaic Virus Movement Protein Functions as a Structural Microtubule-Associated Protein

The 65-kDa carrot microtubule-associated protein forms regularly arranged filamentous cross-bridges between microtubules

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