Microtubules Essay Example | Topics and Well Written Essays - 1500 words - 1

Microtubules - Essay Example aments, which demonstrate diverse turnover rates, are closely associated with actin binding proteins which differ, and it has been postulated that they determine the differences in turnover rates. This plasticity of the internal structure of the actins is responsible for the difference in filament turnover rates in different cellular locations. This is accomplished through direct control of the filament stability and through modulation of protein binding affecting the stability of the filaments (Kueha et al., 2008). These, therefore, are mechanoskelatal proteins which convert energy released by hydrolysis of ATP or from ion gradients and generate mechanical forces. The most important feature of these proteins that while they bind, they carry their own cargo, and hence movement at a specific direction of this protein as a result of microtubular shortening would result in movement of the cargo from one location to the other within the cell. This allows an avenue of movement of the cellular proteins to the target area where further chemical reaction may take place. Thus, this is an example of accessory protein which in association with the cellular microtubules can cause sliding movement between the microtubules that are adjacent and at the same time causes movement of the cytoplasmic particles along a single microtubule to its target (Gibbon, 1988). Recent studies on accessory proteins associated with microtubules demonstrate that cytosolic dyneins are associated with retrograde transmission of intraxonal vesicles within neural tissues, and the forward motion of such vesicles is effected by another accessory protein, namely, kinesins. At the same time, within the brain neural tissues accessory proteins have been located which vary in molecular weights and binding... This essay focuses on the discussion of the microtubules, that on the molecular level comprise of tubulin molecules, which in turn are a heterodimer comprising of globular polypeptides, alpha and beta tubulin which are closely related and tightly linked. Many cellular functions are controlled by these microtubules which essentially are mediated through polymerisation and depolymerisation, which are controlled by nucleotide GTP. Following synthesis, there are molecular rearrangements within these microtubules are stabilized with accessory proteins, which are specific for particular tubulin. In this assignment from different cellular examples, these interactions between the specific accessory proteins and the microtubule molecular structure will be examined in order to describe the structures and functions of these specific accessory proteins. It has been demonstrated in the essay, that within the cell, there is continuous modification of microtubules which is conferred through a proce ss of binding to other proteins. These are known as microtubule associated proteins or accessory proteins. The two main roles that these microtubule-accessory protein complexes perform are stabilization of the microtubular molecular structure against disassembly and more importantly mediation of their interactions with other components of the cell. The most significant and ubiquitous protein associated are ATPases which transduce energy also known as microtubule motor proteins which induce a sliding between adjacent microtubules.