Microtubule polymerization

About: Microtubule polymerization is a research topic. Over the lifetime, 1374 publications have been published within this topic receiving 66063 citations.

Microtubule polymerization dynamics

Abstract: The polymerization dynamics of microtubules are central to their biological functions. Polymerization dynamics allow microtubules to adopt spatial arrangements that can change rapidly in response to cellular needs and, in some cases, to perform mechanical work. Microtubules utilize the energy of GTP hydrolysis to fuel a unique polymerization mechanism termed dynamic instability. In this review, we first describe progress toward understanding the mechanism of dynamic instability of pure tubulin and then discuss the function and regulation of microtubule dynamic instability in living cells.

Visualization of Cellulose Synthase Demonstrates Functional Association with Microtubules

Abstract: Expression of a functional yellow fluorescent protein fusion to cellulose synthase (CESA) in transgenic Arabidopsis plants allowed the process of cellulose deposition to be visualized in living cells Spinning disk confocal microscopy revealed that CESA complexes in the plasma membrane moved at constant rates in linear tracks that were aligned and were coincident with cortical microtubules Within each observed linear track, complex movement was bidirectional Inhibition of microtubule polymerization changed the fine-scale distribution and pattern of moving CESA complexes in the membrane, indicating a relatively direct mechanism for guidance of cellulose deposition by the cytoskeleton

Microtubule Formation in vitro in Solutions Containing Low Calcium Concentrations

Abstract: Isolated rat brain tubulin can be repolymerized in vitro in solutions containing adenosine triphosphate or guanosine triphosphate, magnesium ions, and a good calcium chelator. The extreme sensitivity of tubulin to calcium ions explains the failure of previous efforts to obtain polymerization and suggests a possible mechanism for regulation of microtubule polymerization in vivo.

Modulation of the dynamic instability of tubulin assembly by the microtubule-associated protein tau.

Abstract: Microtubule-associated proteins (MAP), such as tau, modulate the extent and rate of microtubule assembly and play an essential role in morphogenetic processes, such as axonal growth. We have examined the mechanism by which tau affects microtubule polymerization by examining the kinetics of microtubule assembly and disassembly through direct observation of microtubules using dark-field microscopy. Tau increases the rate of polymerization, decreases the rate of transit into the shrinking phase (catastrophe), and inhibits the rate of depolymerization. Tau strongly suppresses the catastrophe rate, and its ability to do so is independent of its ability to increase the elongation rate. Thus, tau generates a partially stable but still dynamic state in microtubules. This state is perturbed by phosphorylation by MAP2 kinase, which affects all three activities by lowering the affinity of tau for the microtubule lattice.

Tau protein function in living cells.

Abstract: Tau protein from mammalian brain promotes microtubule polymerization in vitro and is induced during nerve cell differentiation. However, the effects of tau or any other microtubule-associated protein on tubulin assembly within cells are presently unknown. We have tested tau protein activity in vivo by microinjection into a cell type that has no endogenous tau protein. Immunofluorescence shows that tau protein microinjected into fibroblast cells associates specifically with microtubules. The injected tau protein increases tubulin polymerization and stabilizes microtubules against depolymerization. This increased polymerization does not, however, cause major changes in cell morphology or microtubule arrangement. Thus, tau protein acts in vivo primarily to induce tubulin assembly and stabilize microtubules, activities that may be necessary, but not sufficient, for neuronal morphogenesis.