extrinsic component of external side of plasma membrane

Definition

Target type: cellularcomponent

The component of a plasma membrane consisting of gene products and protein complexes that are loosely bound to its external surface, but not integrated into the hydrophobic region. [GOC:dos, GOC:mah]

The extrinsic component of the external side of the plasma membrane, also known as the ectodomain, is composed of proteins and lipids that are anchored to the outer leaflet of the plasma membrane. These components are not embedded within the membrane itself, but rather associate with the membrane through a variety of mechanisms, such as:

* **Transmembrane domains:** Proteins with transmembrane domains span the lipid bilayer of the plasma membrane and have an ectodomain extending outside the cell.
* **Lipid anchors:** Some proteins are attached to the membrane through lipid modifications, such as glycosylphosphatidylinositol (GPI) anchors or myristoylation.
* **Non-covalent interactions:** Other proteins may associate with the membrane through electrostatic interactions or hydrogen bonds with phospholipid head groups.

The extrinsic components of the external side of the plasma membrane play a critical role in a wide range of cellular processes, including:

* **Cell signaling:** Many receptors and signaling molecules are located in the ectodomain, allowing cells to receive and respond to external stimuli.
* **Cell adhesion:** Proteins in the ectodomain can mediate cell-cell interactions, anchoring cells together and forming tissues.
* **Protection:** The ectodomain can provide a barrier against external threats, such as pathogens and toxins.
* **Transport:** Some proteins in the ectodomain facilitate the transport of molecules across the plasma membrane.

Examples of specific components of the extrinsic component of the external side of the plasma membrane include:

* **Receptors:** For example, growth factor receptors, cytokine receptors, and hormone receptors.
* **Adhesion molecules:** For example, cadherins, integrins, and selectins.
* **Enzymes:** For example, proteases and glycosyltransferases.
* **Antibodies:** Immunoglobulin molecules that bind to specific antigens.

The composition and organization of the ectodomain can vary significantly depending on the cell type and its function.'
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Proteins (1)

Compounds (2)