FIGURE 3:

A possible role for terminal GDP-to-GTP exchange in microtubule catastrophe. (A) GDP-to-GTP exchange on a terminal subunit. (B) To investigate in simulations the possible relevance of terminal GDP-to-GTP exchange, we added it as another possible event in our simulation algorithm. Varying the rate of terminal GDP-to-GTP exchange in simulations with two different GTPase rate constants (green, 0.2 s⁻¹; pink, 0.15 s⁻¹) yielded a marked effect on the predicted frequency of catastrophe, with faster rates of exchange giving less frequent catastrophe.