Tubulin

Structure of tubulin as determined by X-ray crystallography.

Infographic illustrating the role of tubulin in the cell.

Tubulin is a globular protein that is the primary building block of microtubules, which are a component of the cytoskeleton in eukaryotic cells. Tubulin is essential for a variety of cellular processes, including mitosis, intracellular transport, and the maintenance of cell shape.

Structure

Tubulin is a dimer composed of two closely related subunits, _-tubulin and _-tubulin. These subunits polymerize to form microtubules, which are cylindrical structures that can rapidly assemble and disassemble within the cell. The dynamic instability of microtubules is crucial for their function in cellular processes.

Function

Microtubules, formed by tubulin, play a critical role in maintaining the cell's structure, providing platforms for intracellular transport, and segregating chromosomes during cell division. Tubulin also interacts with various microtubule-associated proteins (MAPs) that regulate its stability and function.

Types of Tubulin

In addition to _-tubulin and _-tubulin, there are other types of tubulin, such as _-tubulin, which is involved in the nucleation of microtubules at the centrosome. Other less common forms include _-tubulin and _-tubulin, which have specialized roles in certain organisms.

Comparison of bacterial and eukaryotic microtubules.

Evolution

Tubulin is highly conserved across eukaryotic species, indicating its fundamental role in cellular processes. The evolutionary origin of tubulin is thought to be related to the bacterial protein FtsZ, which is involved in cell division in prokaryotes.

Clinical Significance

Tubulin is a target for several anticancer drugs, such as taxanes and vinca alkaloids, which disrupt microtubule dynamics and inhibit cell division. Mutations in tubulin genes can lead to various diseases, including neurological disorders.

Structure of beta-tubulin from Tetrahymena.

Gamma-tubulin ring complex involved in microtubule nucleation.

Related Pages

• Microtubule
• Cytoskeleton
• Mitosis
• Microtubule-associated protein