Would a tubulin depolymerising agents such as nocodazole reduce the levels of tubulin in cells or do they just reduce the polymerised fraction of tubulin without affecting total tubulin levels?
Molecular Biology of the CellVol. 8, 973-985, June 1997
Nanornolar Concentrations of Nocodazole Alter Microtubule Dynamic Instability In Vivo and In Vitro
Robert J. Vasquez, Bonnie Howell, Anne-Marie C. Yvon,Patricia Wadsworth, and Lynne Cassimeris
From the abstract:
At both microtubule plus and minus ends,perfusion with nocodazole resulted in a dose-dependent decrease in elongation and shortening velocities, increase in pause duration and catastrophe frequency, and decrease in rescue frequency. These effects, which result in an overall decrease in microtubule turnover after nocodazole treatment, suggest that the mitotic block observed is due to a reduction in microtubule dynamic turnover. In addition, the in vitro results are similar tothe effects of increasing concentrations of GDP-tubulin (TuD) subunits on microtubuleassembly. Given that nocodazole increases tubulin GTPase activity, we propose that nocodazole acts by generating TuD subunits that then alter dynamic instability.