tubulin complex

Definition

Target type: cellularcomponent

A heterodimer of tubulins alpha and beta that constitutes the protomer for microtubule assembly. [ISBN:0716731363]

The tubulin complex is a fundamental component of eukaryotic cells, forming the building blocks of microtubules. Microtubules are dynamic, filamentous structures that play crucial roles in a wide array of cellular processes, including:

- **Cell division:** Microtubules form the spindle fibers that separate chromosomes during mitosis and meiosis, ensuring accurate distribution of genetic material to daughter cells.
- **Cell shape and structure:** Microtubules provide structural support to cells, maintaining their shape and contributing to the organization of intracellular organelles.
- **Intracellular transport:** Microtubules serve as tracks for motor proteins like kinesin and dynein, which transport vesicles, organelles, and other cargos throughout the cell.
- **Cilia and flagella:** Microtubules are the core components of cilia and flagella, hair-like structures that enable movement and sensory functions in certain cells.

**Structure of the Tubulin Complex:**

The basic unit of a microtubule is a heterodimer composed of two tubulin proteins: alpha-tubulin and beta-tubulin. These proteins are highly conserved across eukaryotes and exhibit a globular shape. Each tubulin monomer binds a single molecule of GTP (guanosine triphosphate), which plays a vital role in microtubule dynamics.

Alpha-tubulin and beta-tubulin associate head-to-tail to form a dimer, with the alpha-tubulin subunit exposed at one end and the beta-tubulin subunit exposed at the other. These dimers then assemble into protofilaments, linear chains of tubulin dimers. Thirteen protofilaments associate laterally to create a hollow cylindrical structure, the microtubule.

**Microtubule Dynamics:**

Microtubules exhibit dynamic instability, a process characterized by periods of rapid growth (polymerization) and shrinkage (depolymerization). This dynamic behavior is essential for microtubule function and is regulated by factors such as GTP hydrolysis, tubulin concentration, and microtubule-associated proteins (MAPs).

**Microtubule-Associated Proteins (MAPs):**

MAPs are proteins that bind to microtubules and regulate their assembly, stability, and interactions with other cellular components. Different MAPs perform a variety of functions, including:

- **Stabilizing microtubules:** Some MAPs promote microtubule stability by cross-linking protofilaments or binding to the ends of microtubules.
- **Promoting microtubule dynamics:** Other MAPs can promote microtubule depolymerization or regulate the rate of polymerization.
- **Linking microtubules to other cellular structures:** MAPs can connect microtubules to organelles, membranes, and other cytoskeletal components.

**In summary, the tubulin complex is a vital structural and functional component of eukaryotic cells. Its dynamic nature, combined with the influence of MAPs, allows microtubules to perform a wide range of essential roles in cellular processes.**'
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Proteins (1)

Compounds (18)