extracellular matrix

Definition

Target type: cellularcomponent

A structure lying external to one or more cells, which provides structural support, biochemical or biomechanical cues for cells or tissues. [GOC:BHF, GOC:mah, GOC:rph, NIF_Subcellular:nlx_subcell_20090513, PMID:21123617, PMID:28089324]

The extracellular matrix (ECM) is a complex network of macromolecules that provides structural support, regulates cell behavior, and plays a crucial role in tissue development and function. It is found in all multicellular organisms and is composed of various components, including proteins, carbohydrates, and lipids.

**Proteins:** The major protein components of the ECM are:

* **Collagens:** These are fibrous proteins that provide tensile strength and structural integrity to the ECM. There are many types of collagen, each with its own specific function and distribution. For example, type I collagen is the most abundant type and is found in skin, bone, and tendons, while type IV collagen forms a mesh-like network in basement membranes.
* **Elastin:** This protein provides elasticity and flexibility to the ECM, allowing tissues to stretch and recoil. It is found in organs that require flexibility, such as the lungs, blood vessels, and skin.
* **Fibronectin:** This glycoprotein acts as a bridge between cells and the ECM. It interacts with cell surface receptors, such as integrins, and helps to organize the ECM. It also plays a role in cell adhesion, migration, and differentiation.
* **Laminin:** This glycoprotein is a major component of basement membranes, which are specialized ECM layers that surround epithelial tissues, blood vessels, and muscles. It interacts with other ECM components, such as collagen and fibronectin, and provides a scaffold for cell adhesion and migration.
* **Proteoglycans:** These molecules consist of a core protein attached to long chains of glycosaminoglycans (GAGs). GAGs are highly negatively charged polysaccharides that attract water, giving the ECM its gel-like consistency. Proteoglycans also play a role in regulating cell signaling and growth.

**Carbohydrates:** The ECM also contains a variety of carbohydrates, including GAGs, hyaluronic acid, and glycoproteins. GAGs, as mentioned above, are highly negatively charged polysaccharides that attract water, giving the ECM its gel-like consistency. Hyaluronic acid is a large, unbranched GAG that provides hydration and lubricates the ECM. Glycoproteins are proteins that are covalently linked to carbohydrates, and they play a variety of roles in the ECM, including cell adhesion, migration, and signaling.

**Lipids:** The ECM also contains lipids, which contribute to its structural integrity and signaling functions. Lipids can be found in the form of phospholipids, which form membranes around cells and organelles, and cholesterol, which helps to regulate membrane fluidity.

**Cellular Components:** The ECM is not simply a passive scaffold; it is a dynamic and interactive environment that influences cell behavior. Cells interact with the ECM through specialized receptors on their surface, such as integrins. These receptors bind to ECM components, transmitting signals into the cell that regulate its behavior. This signaling can affect processes such as cell adhesion, migration, proliferation, differentiation, and apoptosis.

The ECM is also a reservoir for growth factors and other signaling molecules. These molecules can be released from the ECM, or they can be bound to ECM components and released upon specific stimuli. This allows the ECM to act as a signaling center, regulating cell behavior in its immediate environment.

In summary, the extracellular matrix is a complex and dynamic structure that provides structural support, regulates cell behavior, and plays a crucial role in tissue development and function. Its composition and organization vary depending on the tissue type, and its interactions with cells are critical for maintaining tissue homeostasis and function.'
"

Proteins (29)

Compounds (209)