@article {1688,
	title = {Three-dimensional microtubule behavior in Xenopus egg extracts reveals four dynamic states and state-dependent elastic properties.},
	journal = {Biophysical Journal},
	volume = {95},
	year = {2008},
	month = {2008 Aug},
	pages = {1474-86},
	abstract = {<p>Although microtubules are key players in many cellular processes, very little is known about their dynamic and mechanical properties in physiological three-dimensional environments. The conventional model of microtubule dynamic instability postulates two dynamic microtubule states, growth and shrinkage. However, several studies have indicated that such a model does not provide a comprehensive quantitative and qualitative description of microtubule behavior. Using three-dimensional laser light-sheet fluorescence microscopy and a three-dimensional sample preparation in spacious Teflon cylinders, we measured microtubule dynamic instability and elasticity in interphase Xenopus laevis egg extracts. Our data are inconsistent with a two-state model of microtubule dynamic instability and favor an extended four-state model with two independent metastable pause states over a three-state model with a single pause state. Moreover, our data on kinetic state transitions rule out a simple GTP cap model as the driving force of microtubule stabilization in egg extracts on timescales of a few seconds or longer. We determined the three-dimensional elastic properties of microtubules as a function of both the contour length and the dynamic state. Our results indicate that pausing microtubules are less flexible than growing microtubules and suggest a growth-speed-dependent persistence length. These data might hint toward mechanisms that enable microtubules to efficiently perform multiple different tasks in the cell and suggest the development of a unified model of microtubule dynamics and microtubule mechanics.</p>
},
	keywords = {Animals, Elasticity, Imaging, Mechanical, Microtubules, Ovum, Stress, Three-Dimensional, Xenopus laevis},
	issn = {1542-0086},
	doi = {10.1529/biophysj.107.128223},
	author = {Keller, Philipp J and Pampaloni, Francesco and Lattanzi, Gianluca and Stelzer, Ernst H K}
}
