User:Andy Maloney/Notebook/Lab Notebook of Andy Maloney/2009/05/08/Kinetic analysis of GTP hydrolysis associated with tubulin polymerization review

Disclaimer
These are my thoughts on this paper. Read the paper before you read my comments please.

Paper
Kinetic analysis of GTP hydrolysis associated with tubulin polymerization

Review
So I started out with this question
 * Question: How does tubulin polymerize into microtubules?

This paper gives me at least a reference for what is already known in the field and that is, tubulin carries GTP on both its $$\alpha$$ and $$\beta$$ subunits. When two tubulin heterodimers combine, the $$\beta$$ site hydrolyzes GTP to form GDP. I think the GDP gets stuck but I'm not sure.
 * They note that microtubules can be stabilized with nonhydrolyzable analogues of GTP such as GMPCPP.
 * I got another reference where they actually show GTP hydrolysis occurs at the $$\beta$$ subunit, Reference.
 * They also state that free GTP in solution can be exchanged with bound GTP on tubulin that has been polymerized into microtubules.

Take home This was a nice paper that answered the question for me of "where are the references that say GTP is needed". Of course, I still don't understand why polymerization needs magnesium ions.