In this study, a two-state mechanochemical model is presented to describe the dynamic properties of microtubule (MT) growth in cells. The MT switches between two states, assembly state and disassembly state. In assembly state, the growth of microtubule includes two processes:  GTP-tubulin binding to the tip of protofilament (PF) and conformational change of PF, during which the penultimate GTP is hydrolyzed and the first tubulin unit that curls out the MT surface is rearranged into MT surface using the energy released from GTP hydrolysis . In disassembly state, the shortening of microtubule is also described by two processes, the release of GDP-tibulin from the tip of PF and one new tubulin unit curls out from the MT surface. Switches between these two states, which are usually called rescue and catastrophe, happen stochastically with external force dependent rates. Using this two-state model with parameters obtained by fitting the recent experimental data, detailed properties of MT growth are obtained, we find that MT is mainly in assembly state, its mean growth velocity increases with external force and GTP-tubulin concentration, MT will shorten in average without external force. To know more about the external force and GTP concentration dependent MT growth properties , and for the sake of  experimental verification of this two-state model, eight {\it critical forces} are defined and numerically discussed.
In this study, a two-state mechanochemical model is presented to describe the dynamic instability of microtubules (MTs) in cells. The MTs switches between two states, assembly state and disassembly state. In assembly state, the growth of MTs includes two processes: free GTP-tubulin binding to the tip of protofilament (PF) and conformation change of PF, during which the first tubulin unit which curls outwards is rearranged into MT surface using the energy released from the hydrolysis of GTP in the penultimate tubulin unit . In disassembly state, the shortening of MTs includes also two processes, the release of GDP-tibulin from the tip of PF and one new tubulin unit curls out of the MT surface. Switches between these two states, which are usually called rescue and catastrophe, happen stochastically with external force dependent rates. Using this two-state model with parameters obtained by fitting the recent experimental data, detailed properties of MT growth are obtained, we find that MT is mainly in assembly state, its mean growth velocity increases with external force and GTP-tubulin concentration, MT will shorten in average without external force. To know more about the external force and GTP-tubulin concentration dependent properties of MT growth , and for the sake of the future experimental verification of this two-state model, eleven {\it critical forces} are defined and numerically discussed.
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properties of microtubule (MT) growth
instability of microtubules (MTs)
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MT
MTs
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microtubule
MTs
A
free
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conformational
conformation
D
penultimate GTP is hydrolyzed and the
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that curls out the MT surface
which curls outwards
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GTP hydrolysis
the hydrolysis of GTP in the penultimate tubulin unit
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microtubule is also described by
MTs includes also
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from
of
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GTP concentration dependent MT growth properties
GTP-tubulin concentration dependent properties of MT growth
A
the future
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eight
eleven