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The tubulin protein dimers of the microtubules have hydrophobic pockets that may contain delocalized π electrons. Tubulin has other, smaller non-polar regions, for example 8 tryptophans per tubulin, which contain π electron-rich indole rings distributed throughout tubulin with separations of roughly 2 nm.
The C protein plays an important role in the retrograde transport of vesicles and is also known as cytoplasmic dynein. MAP-2 proteins are located in the dendrites and in the body of neurons, where they bind with other cytoskeletal filaments. The MAP-4 proteins are found in the majority of cells and stabilize microtubules.
In 1903, Nikolai K. Koltsov proposed that the shape of cells was determined by a network of tubules that he termed the cytoskeleton. The concept of a protein mosaic that dynamically coordinated cytoplasmic biochemistry was proposed by Rudolph Peters in 1929 [12] while the term (cytosquelette, in French) was first introduced by French embryologist Paul Wintrebert in 1931.
Microtubules are assembled from dimers of α- and β-tubulin. These subunits are slightly acidic, with an isoelectric point between 5.2 and 5.8. [14] Each has a molecular weight of approximately 50 kDa. [15] To form microtubules, the dimers of α- and β-tubulin bind to GTP and assemble onto the (+) ends of microtubules while in the GTP-bound ...
Several proteins are involved in formatting the γ-TuRC and temporal and spatial control of microtubule nucleation. These include, for example, coiled-coil proteins with structural functions and regulatory proteins, such as components of the Ran cycle. NEDD1 recruits the γ-TuRC to the centrosome by binding to γ-tubulin. [14] [15]
Tau proteins stabilize microtubules, and thus shift the reaction kinetics in favor of addition of new subunits, accelerating microtubule growth. Tau has the additional function of facilitating bundling of microtubules within the nerve cell. The function of tau has been linked to the neurological condition Alzheimer's disease.
The building-block of the axoneme is the microtubule; each axoneme is composed of several microtubules aligned in a characteristic pattern known as the 9+2 axoneme as shown in the image at right. Nine sets of doublet microtubules (a specialized structure consisting of two linked microtubules) form a ring around a central pair of single ...
He was the Mallinckrodt Professor of Physics at Harvard University and Adjunct Professor of Optical Sciences at the University of Arizona. Born in New York City, he was awarded one half of the 2005 Nobel Prize in Physics "for his contribution to the quantum theory of optical coherence ", with the other half shared by John L. Hall and Theodor W ...