Question

If microtubules are inherently unstable when GTP on its dimer subunits has been hydrolyzed to GDP, why do they sometimes persist?

1) The dimers rephosphorylate while still part of the microtubule.
2) Covalent bonds hold them together.
3) MAPs, if present, act like stabilizing factors that prevent microtubule disassembly.
4) MAPs, if present, rephosphorylate tubulin dimer subunits in the microtubule.

Answer 1

Microtubules can persist even after GTP is hydrolyzed to GDP due to factors such as rephosphorylation of tubulin dimers, covalent bonds, and the presence of Microtubule-Associated Proteins (MAPs) that stabilize the microtubule.

Step-by-step explanation:

The persistence of microtubules even after the hydrolysis of GTP to GDP can be attributed to several factors:

1. The rephosphorylation of the tubulin dimers that make up the microtubule can occur while they are still part of the microtubule structure.
2. Covalent bonds between the tubulin subunits also help to hold the microtubule together.
3. Microtubule-Associated Proteins (MAPs), if present, act as stabilizing factors that prevent microtubule disassembly.
4. MAPs, if present, can also rephosphorylate the tubulin dimer subunits in the microtubule, contributing to their stability.