Microtubule

Microtubules are long, hollow cylindrical polymers composed primarily of α-tubulin and β-tubulin heterodimers. They are a major component of the eukaryotic cytoskeleton, typically consisting of 13 protofilaments arranged around a central lumen. Microtubules exhibit intrinsic polarity with a fast-growing plus end and a slow-growing minus end. Their dynamic instability—cycles between growth and shrinkage—is essential for their cellular functions. Microtubules provide structural support for the cell, serve as tracks for motor proteins such as kinesin and dynein that mediate intracellular transport, form the mitotic spindle required for chromosome segregation during cell division, and constitute the core structure within cilia and flagella enabling motility. Because they play critical roles in cell proliferation and migration, they are important therapeutic targets—especially in cancer therapy where drugs disrupt their dynamics to inhibit tumor growth.

Other names

Tubulin polymerCytoskeletal microtubuleMT (less common)

Mechanism of action involves either stabilization of microtubules to prevent depolymerization (e.g., paclitaxel) or inhibition of tubulin polymerization leading to depolymerization/disassembly (e.g., vincristine, colchicine).