Question

Your friend works in a lab that examines microtubules. She decides to grow some microtubules in vitro. After growing some with normal (Alpha-Beta)‐tubulin dimers bound to GTP, she replaces them with only GMPCPP bound (Alpha-Beta)‐tubulin dimers. GMPCPP is analog of GTP that cannot be hydrolyzed to GDP

Will she observe dynamic instability in her GMPCPP‐bound microtubules? Explain.

Answer 1

No, she will not observe dynamic instability

Step-by-step explanation:

Microtubules are dynamic polymers formed by the assembly of α‐ and β‐tubulin, which alternate between growing and shrinking states. These states are regulated by the hydrolysis of GTP bound to β-tubulin. In consequence, the dynamic behavior of the microtubules depends on the binding and hydrolysis of GTP by β-tubulin, which alters the conformation of tubulin molecules. The Guanylyl 5′-α,β-methylenediphosphonate (GMPCPP) is a slowly hydrolyzing analog of GTP that binds to tubulin with an affinity four to eightfold lower than GTP, which is used to produce stable microtubules that resist their depolymerization. When microtubules are polymerized with GMPCPP, they do not undergo dynamic instability, because GTP hydrolysis is necessary for their switching behavior.