The effect of solution composition on microtubule dynamic instability.

摘要: The exchange of tubulin dimer into steady-state microtubules was studied over a range solution conditions, in order to assess the effects various common buffer components on dynamic instability microtubules. In comparison with standard conditions (100 mM-Pipes buffer, pH 6.5, containing 0.1 mM-EGTA, 1.8 mM-MgC12 and 1 M-glycerol), rate extent exchange, thus instability, are suppressed by increasing concentration glycerol above 2 M. Exchange is enhanced addition further Mg2+ (up 17 mM) or Ca2+ 0.4 mM). Phosphate ion (150 has relatively little effect behaviour microtubules, as judged method. findings interpreted within framework Lateral Cap model for microtubule terms these changes intrinsic constants system. By contrast, depends selectively value dissociation constant tubulin-GDP. A decrease hence activity, associated decreased this constant, vice versa. results also show good agreement predictions treating observed variations properties individual induced different conditions.