Growing Microtubule Ends are Normally Stabilized By

Question

Growing microtubule ends are normally stabilized by:
A)a GDP cap.
B)a GTP cap.
C)phosphorylation of tubulin subunits.
D)γ-tubulin.

Accepted Answer

Growing microtubule ends are stabilized by a GTP cap, which means that the growing end of the microtubule is made up of GTP-bound tubulin subunits. Once these subunits are hydrolyzed to GDP, the microtubule will become unstable and potentially depolymerize. Therefore, choice B is the correct answer. The other choices (A, C, and D) are not correct as they do not play a role in stabilizing the growing microtubule end.