desmosome

Definition

Target type: cellularcomponent

A cell-cell junction in which: on the cytoplasmic surface of each interacting plasma membrane is a dense plaque composed of a mixture of intracellular anchor proteins; a bundle of keratin intermediate filaments is attached to the surface of each plaque; transmembrane adhesion proteins of the cadherin family bind to the plaques and interact through their extracellular domains to hold the adjacent membranes together by a Ca2+-dependent mechanism. [GOC:mah, GOC:mtg_muscle, ISBN:0815332181]

Desmosomes are complex intercellular junctions that provide strong adhesion between epithelial cells, contributing to tissue integrity and preventing cell separation under mechanical stress. They are characterized by a dense, electron-dense plaque-like structure on the cytoplasmic side of the plasma membrane, which serves as an anchoring site for the desmosomal cadherins.

The major components of the desmosome cellular component include:

- **Desmosomal cadherins:** These transmembrane proteins, primarily desmoglein and desmocollin, form the core of the desmosome. They interact with each other in a calcium-dependent manner, mediating cell-cell adhesion. The extracellular domains of desmoglein and desmocollin bind to the same molecules on the opposing cell, while their cytoplasmic tails link to the plaque.

- **Plaque proteins:** These proteins, located on the cytoplasmic side of the plasma membrane, are essential for anchoring desmosomal cadherins and linking them to the intermediate filament cytoskeleton. Key plaque proteins include:
- **Plakoglobin:** A cytoplasmic protein that interacts with both desmoglein and desmocollin, bridging the connection between the cadherins and other plaque proteins.
- **Plakophilin:** Another cytoplasmic protein that binds to plakoglobin and desmoglein, contributing to the stability of the desmosome structure.
- **Desmoplakin:** A large protein that directly links the desmosome to the intermediate filament cytoskeleton. Desmoplakin interacts with plakoglobin and plakophilin, forming a complex that anchors the desmosome to the cell's internal structural framework.

- **Intermediate filaments:** These rope-like protein polymers provide mechanical strength to cells and tissues. In epithelial cells, the major type of intermediate filament is keratin. Keratin filaments connect to desmosomes via desmoplakin, forming a continuous network throughout the cell and contributing to the overall tensile strength of the tissue.

The interaction of these components creates a robust and highly stable intercellular junction. Desmosomes play a crucial role in maintaining tissue integrity, particularly in tissues subjected to mechanical stress, such as skin, heart, and muscle.'
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Proteins (2)

Compounds (3)