Thickness distribution of actin bundles in vitro |
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Authors: | Lior Haviv Nir Gov Yaron Ideses Anne Bernheim-Groswasser |
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Institution: | (1) Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel;(2) Weizmann Institute of Science, Rehovot, Israel |
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Abstract: | Bundles of filamentous actin form the primary building blocks of a broad range of cytoskeletal structures, including filopodia,
stereocilia and microvilli. In each case, the cell uses specific associated proteins to tailor the dynamics, dimensions and
mechanical properties of the bundles to suit a specific cellular function. While the length distribution of actin bundles
was extensively studied, almost nothing is known about the thickness distribution. Here, we use high-resolution cryo-TEM to
measure the thickness distribution of actin/fascin bundles, in vitro. We find that the thickness distribution has a prominent
peak, with an exponential tail, supporting a scenario of an initial fast formation of a disc-like nucleus of short actin filaments,
which only later elongates. The bundle thicknesses at steady state are found to follow the distribution of the initial nuclei
indicating that no lateral coalescence occurs. Our results show that the distribution of bundles thicknesses can be controlled
by monitoring the initial nucleation process. In vivo, this is done by using specific regulatory proteins complexes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Actin bundles Thickness distribution Non-equilibrium thermodynamics Cryo-TEM |
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