GTPases have a branch of tubulin that belong to the same family, and those tubulins polymerize into microtubules which are small hollow cylindrical structures which a diameter of 25 nm
Microtubules exhibit structural and functional polarity like actin microfilaments
Protofilaments are formed by dimeric aB-tubulin which interact with end to end, and protofilaments are laterally associated with microtubules
The (+) of microtubules lose and gain subunits, and microtubules have structural polarity
The critical concentration of aB- tubulin affects the assembly and disassembly of microtubules:
If the Cc is above, the microtubules assemble
If the Cc is below, the microtubules disassemble
There are two situations that are shown regarding tubulin concentrations:
Tread milling, subunits increasing and decreasing
Dynamic instability, lengthening, and shortening of the oscillation
GTP bound to B-tubulin on the (+) side or if the GTP has been hydrolyzed to GDP affects the balance in the growth and shrinkage of microtubules
MAPs (microtubule-associated proteins) affect the stability of and organize microtubules:
MAPs can control cytosolic microtubule depolymerization
They can also organize and crosslink microtubules into bundles and membranes for the mediation of filaments in the membrane
Drugs like colchicine and taxol can help with cancer as they disrupt microtubules and provide an antimitotic effect