contractile ring

Definition

Target type: cellularcomponent

A cytoskeletal structure composed of filamentous protein that forms beneath the membrane of many cells or organelles, in the plane of cell or organelle division. Ring contraction is associated with centripetal growth of the membrane that divides the cytoplasm of the two daughter cells or organelles. [GOC:mah, ISBN:0123645859, ISBN:0792354923, PMID:10791428, PMID:17913889]

The contractile ring is a dynamic, actomyosin-based structure that forms during cytokinesis, the final stage of cell division. It is responsible for constricting the cell membrane and dividing the cytoplasm into two daughter cells. The cellular components of the contractile ring include:

* **Actin filaments:** These are the primary structural components of the ring. They are arranged in a dense, circumferential band around the cell equator.
* **Myosin II:** This motor protein binds to actin filaments and generates the force required for ring contraction.
* **Regulatory proteins:** These proteins control the assembly and disassembly of the contractile ring, as well as the activity of myosin II. Key regulatory proteins include:
* **RhoA:** A small GTPase that activates the assembly of the contractile ring.
* **Formins:** Proteins that nucleate and elongate actin filaments.
* **Profilins:** Proteins that promote actin polymerization.
* **Cofilin:** A protein that depolymerizes actin filaments.
* **Other proteins:** In addition to actin, myosin, and regulatory proteins, the contractile ring also contains other proteins that play important roles in its function. These include:
* **Membrane-associated proteins:** These proteins anchor the contractile ring to the cell membrane.
* **Linker proteins:** These proteins connect actin filaments to other cytoskeletal components, such as microtubules.
* **Signaling proteins:** These proteins relay signals from the cell's interior to the contractile ring, regulating its activity.

The precise composition and organization of the contractile ring can vary depending on the cell type and stage of cytokinesis. However, the basic structure and function of the ring are conserved in most eukaryotic cells.'
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Proteins (2)

Compounds (2)