Regulation of Microtubule Dynamics Pathway

What are microtubules?

Microtubules are the major components of cytoskeleton.they are found in the eukaryotic cells are are involved in mitosis,maintenance of cell shape and intracellular transport. They are formed by the polymerization of a dimer of two globular proteins alpha and beta tubulin into protofilaments that can then be associated laterally to form a hollow tube. Due to their participation in most cellular functions,they must be regulated in response to extracellular and intracellular signals.because of complexity and numerosity of microtubule dynamics,the connection and regulation of microtubule dynamics remains indistinct.

The majority of microtubules are formed from organizing centers. The most common microtubule activity is dynamic instability, which is characterized by sluggish plus end expansion followed by rapid depolymerization (“catastrophe”) and subsequent rescue. Although the minus ends of microtubules exhibit dynamic instability, albeit at a slower pace than the plus ends, the minus ends are often capped and attached to MT organizing centers, and so do not frequently engage in microtubule dynamics.

The balance between dynamically unstable and stable microtubules is mostly controlled by proteins that bind either tubulin dimers or assembled microtubules. Stathmin, which sequesters tubulin and improves MT dynamics by increasing catastrophe frequency, and collapsin response mediator protein (CRMP2), which promotes tubulin dimer addition to microtubule plus ends, are two proteins that bind tubulin dimers. Other proteins that interact with assembled MTs include those that bundle MTs (e.g., MAP1c), those that stabilize MTs (e.g., tau), and those that keep MTs dynamic (MAP1b). GSK-3, a kinase that is normally active under baseline growth circumstances but becomes locally inactive in response to cues that promote MT growth and dynamics, is a key signaling route that governs MT dynamics.