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Spatial variation of microtubule depolymerization in large asters

delete2021-04-19
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K
Keisuke Ishihara *
F
Franziska Decker
P
Paulo Caldas
J
James F. Pelletier
M
Martin Loose
J
Jan Brugués
T
Timothy J. Mitchison
DOI:10.1091/mbc.E20-11-0723delete
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Abstract

Abstract

En 中文
Microtubule plus-end depolymerization rate is a potentially important target of physiological regulation, but it has been challenging to measure, so its role in spatial organization is poorly understood. Here we apply a method for tracking plus ends based on time difference imaging to measure depolymerization rates in large interphase asters growing in Xenopus egg extract. We observed strong spatial regulation of depolymerization rates, which were higher in the aster interior compared with the periphery, and much less regulation of polymerization or catastrophe rates. We interpret these data in terms of a limiting component model, where aster growth results in lower levels of soluble tubulin and microtubule-associated proteins (MAPs) in the interior cytosol compared with that at the periphery. The steady-state polymer fraction of tubulin was similar to 30%, so tubulin is not strongly depleted in the aster interior. We propose that the limiting component for microtubule assembly is a MAP that inhibits depolymerization, and that egg asters are tuned to low microtubule density.
Keywords:
DYNAMIC INSTABILITY
CYTOPLASMIC VOLUME
SPINDLE SIZE
PROTEIN
PHOSPHORYLATION
TUBULIN
KINASE
GROWTH
MAP4
NUCLEATION
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Journal

Molecular Biology of the Cell cover
Molecular Biology of the Cell
IF:
2.7
Papers:
1.0W
Citations:
2.4W

Organization

H
Harvard University
Scholars:
26.5W
Papers: 22.0W
Citations: 28.7W
M
Max Planck Society
Scholars:
8.2W
Papers: 7.7W
Citations: 3.3W
H
Harvard Medical School
Scholars:
6.5W
Papers: 4.8W
Citations: 91
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