Mikrotubulusai

Mikrotubulusai, the Hungarian term for microtubules, are hollow, rigid cylindrical polymers that form part of the cytoskeleton in eukaryotic cells. They are built from α-tubulin and β-tubulin dimers that assemble into protofilaments, which curl around to create a hollow tube about 25 nanometers in diameter. Microtubules are dynamic structures that undergo phases of growth and shrinkage, a property known as dynamic instability. GTP-bound tubulin adds to the rapidly growing plus end; after incorporation, the bound GTP is hydrolyzed to GDP, which destabilizes the lattice and can trigger shrinkage. The minus ends are typically anchored at microtubule organizing centers, most notably the centrosome in animal cells, while plus ends explore the cytoplasm.

In cells, mikrotubulusai provide mechanical support and serve as tracks for intracellular transport. Motor proteins such as kinesin and dynein move along microtubules, carrying cargos like vesicles, organelles, and chromosomes. Microtubules form the mitotic spindle during cell division, enabling chromosome alignment and segregation, and they extend from the bases of cilia and flagella to form the axoneme that drives motion in motile cells.

Regulation of microtubule dynamics involves microtubule-associated proteins, severing enzymes, and post-translational modifications. Clinically, microtubules are targets of anticancer drugs, including taxanes that stabilize microtubules and vinca alkaloids that prevent polymerization. Dysregulation of microtubule function has implications for neurobiology and disease, including neurodegenerative conditions where cytoskeletal stability is affected.