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Monotonic versus oscillating microtubule assembly: a cryo‐electron microscope study
Author(s) -
Wade R.H.,
Pirollet Fabienne,
Margolis Robert L.,
Garel JeanRenaud,
Job Didier
Publication year - 1989
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/j.1768-322x.1989.tb00768.x
Subject(s) - microtubule , tubulin , gtp' , monotonic function , biophysics , biology , oscillation (cell signaling) , polymerization , microtubule polymerization , physics , microbiology and biotechnology , biochemistry , nuclear magnetic resonance , mathematics , mathematical analysis , enzyme , polymer
Depending on the free GTP concentration, microtubules can assemble following either a monotonic or an oscillatory mode. We have used cryoelectron microscopy to compare the tubulin assemblies characteristic of each polymerization pathway. We focus on the first assembly peak. At this particular time point, despite their strikingly different subsequent evolution, both systems are similar with regard to the extent of tubulin polymerization and to the microtubule length distribution. The present study shows that whilst the observed microtubule structures are the same in both systems, the oscillatory system shows quantities of closed ring‐like tubulin oligomers, far in excess of those observed in the monotonic system. Furthermore, the conversion of the oscillating system to a monotonic one by GTP addition during the first oscillation is accompanied by a marked decrease in the number of rings. Based on these results we propose that the GTP dependent step which governs microtubule oscillations is the opening of inactive tubulin oligomers.