TY  - JOUR
AU  - Obermann, H.
AU  - Mandelkow, E. M.
AU  - Lange, G.
AU  - Mandelkow, E.
TI  - Microtubule oscillations. Role of nucleation and microtubule number concentration
JO  - The journal of biological chemistry
VL  - 265
IS  - 8
SN  - 0021-9258
CY  - Bethesda, Md.
PB  - Soc.
M1  - PUBDB-2017-05721
SP  - 4382-4388
PY  - 1990
N1  - HASYLAB
AB  - Microtubules are capable of performing synchronized oscillations of assembly and disassembly which has been explained by reaction mechanisms involving tubulin subunits, oligomers, microtubules, and GTP. Here we address the question of how microtubule nucleation or their number concentration affects the oscillations. Assembly itself requires a critical protein concentration (Cc), but oscillations require in addition a critical microtubule number concentration (CMT). In spontaneous assembly this can be achieved with protein concentrations Cos well above the critical concentration Cc because this enhances the efficiency of nucleation. Seeding with microtubules can either generate oscillations or suppress them, depending on how the seeds alter the effective microtubule number concentration. The relative influence of microtubule number and total protein concentrations can be varied by the rate at which assembly conditions are induced (e.g. by a temperature rise): Fast T-jumps induce oscillations because of efficient nucleation, slow ones do not. Oscillations become damped for several reasons. One is the consumption of GTP, the second is a decrease in microtubule number, and the third is that the ratio of microtubules in the two phases (growth-competent and shrinkage-competent) approach a steady state value. This ratio can be perturbed, and the oscillations restarted, by a cold shock, addition of seeds, addition of GTP, or fragmentation. Each of these is equivalent to a change in the effective microtubule number concentration.
KW  - Macromolecular Substances (NLM Chemicals)
KW  - Microtubule Proteins (NLM Chemicals)
KW  - Tubulin (NLM Chemicals)
KW  - Guanosine Diphosphate (NLM Chemicals)
KW  - Guanosine Triphosphate (NLM Chemicals)
LB  - PUB:(DE-HGF)16
C6  - pmid:2307670
UR  - https://bib-pubdb1.desy.de/record/329083
ER  -