Cell junction

(cell and molecular biology) A specialized site on a cell at which it is attached to another cell or to the extracellular matrix.

Cell junctions are the specialized connections between the plasma membranes of adjoining cells. The three general types of cell junctions are tight junctions, anchoring junctions, and communicating junctions. Tight junctions bind cells together, forming a barrier that is leak-proof. For example, tight junctions form the lining of the digestive tract, preventing the contents of the intestine from entering the body. Anchoring (or adhering) junctions link cells together, enabling them to function as a unit and forming tissue, such as heart muscle or the epithelium that comprises skin. Communicating (or gap) junctions allow rapid chemical and electrical communication between cells. They consist of channels that connect the cytoplasm of adjacent cells.

A cell junction (also called Homophilic binding) is a type of structure that exists within the tissue of a multicellular organism. They consist of protein complexes and provide contact between neighbouring cells, between a cell and the extracellular matrix, or they build up the paracellular barrier of epithelia and control the paracellular transport. Cell junctions are especially abundant in epithelial tissues.

In vertebrates, there are three major types of cell junctions:

• Adherens junctions and Desmosomes (Anchoring Junctions)
• Gap junctions^[1] (Communicating Junction)
• Tight junctions (Occluding Junctions)

Invertebrates have several other types of specific junctions, for example Septate junctions or the CeAJ (C. elegans apical junction).

Cell junction molecules

The molecules responsible for creating cell junctions include various cell adhesion molecules.

References

1. ^ Andrew L Harris and Darren Locke (2009). Connexins, A Guide. New York: Springer. pp. 574. ISBN 978-1-934115-46-6. http://www.springer.com/978-1-934115-46-6. 

External links

• NIH
• MeSH Intercellular+Junctions
• MeSH Cell-Matrix+Junctions

v • d • e Histology: epithelial tissue Types Columnar (simple, stratified) · Cuboidal (simple, stratified) · Pseudostratified (Respiratory) · Squamous (simple, stratified) · Transitional/Urothelium · Olfactory · Corneal Features Lateral/cell-cell Tight junction (Claudin, Occludin) · Adherens junction (Cadherin) · Desmosome (Desmoplakin, Plakoglobin, Tonofibril, Desmoglein) · Gap junction (Connexon, Connexin) Basal/cell-matrix Basal lamina · Hemidesmosome (Tonofibril) · Focal adhesion · Costamere Apical Cilia · Microvilli · Stereocilia

v • d • e Structures of the cell membrane Caveolae/Coated pits - Cell junctions - Glycocalyx - Lipid raft/microdomains - Membrane contact sites - Membrane nanotubes - Myelin sheath - Nodes of Ranvier - Nuclear envelope - Phycobilisomes - Porosomes

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