In cancer, the tubulin is significant for sustaining the cell. Therefore researchers target it, but often only its beta subunit, not its alpha subunit.
It is not researchers that target beta-tubulin but nature. In fact, the majority of the natural compounds targeting cytoskeleton have as a binding site beta-tubulin, in three different regions. Microtubules have plus and minus ends. The plus end is the region of the microtubules involved in the polymerization of new tubulin subunits and the interaction with MAP (microtubule-associated proteins) and other factors. The plus ends of microtubules are exposed to the external interaction while the alpha subunit at the plus end are minimally accessible. Moreover, tubulin is a GTPase. In the alpha subunit the binding of GTP is not interchangeable. On the other hand in the beta GTP can be exchanged and this phenomenon regulates the dynamics of microtubules and the equilibrium between shortening and elongation. Therefore, if you want to interfere with the microtubules using a small molecule the easiest approach, abundantly explored by nature in thousand years of combinatorial chemistry, is to design molecules against beta-tubulin. This does not mean that alpha-tubulin is completely passive. Indeed, there are point mutations in the alpha which also interfere in the assembly of tubulin polymers and the microtubule dynamics. Please also note that there is no one beta-tubulin gene but at least seven. This confers to the system an extreme flexibility and the possibility of regulating the amount of the different isotypes to confer to the system extended communication capabilities and adaptation to different environments. Accordingly if you compare the tubulin composition in neurons and spermatozoa it is very different from those of the skin epithelial cells. It is like an alphabet where the use of single letters can make complex texts (it is referred to as the tubulin code) to respond to the functional needs of the cells.
It is not researchers that target beta-tubulin but nature. In fact, the majority of the natural compounds targeting cytoskeleton have as a binding site beta-tubulin, in three different regions. Microtubules have plus and minus ends. The plus end is the region of the microtubules involved in the polymerization of new tubulin subunits and the interaction with MAP (microtubule-associated proteins) and other factors. The plus ends of microtubules are exposed to the external interaction while the alpha subunit at the plus end are minimally accessible. Moreover, tubulin is a GTPase. In the alpha subunit the binding of GTP is not interchangeable. On the other hand in the beta GTP can be exchanged and this phenomenon regulates the dynamics of microtubules and the equilibrium between shortening and elongation. Therefore, if you want to interfere with the microtubules using a small molecule the easiest approach, abundantly explored by nature in thousand years of combinatorial chemistry, is to design molecules against beta-tubulin. This does not mean that alpha-tubulin is completely passive. Indeed, there are point mutations in the alpha which also interfere in the assembly of tubulin polymers and the microtubule dynamics. Please also note that there is no one beta-tubulin gene but at least seven. This confers to the system an extreme flexibility and the possibility of regulating the amount of the different isotypes to confer to the system extended communication capabilities and adaptation to different environments. Accordingly if you compare the tubulin composition in neurons and spermatozoa it is very different from those of the skin epithelial cells. It is like an alphabet where the use of single letters can make complex texts (it is referred to as the tubulin code) to respond to the functional needs of the cells.
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