Adherens junctions (or zonula adherens, intermediate junction, or "belt desmosome") are protein complexes that occur at cell–cell junctions, cell–matrix junctions in epithelial and endothelial tissues, usually more basal than tight junctions. An adherens junction is defined as a cell junction whose cytoplasmic face is linked to the

actin Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of ov ...

cytoskeleton. They can appear as bands encircling the cell (zonula adherens) or as spots of attachment to the extracellular matrix (focal adhesion). Adherens junctions uniquely disassemble in uterine epithelial cells to allow the blastocyst to penetrate between epithelial cells. A similar cell junction in non-epithelial, non-endothelial cells is the fascia adherens. It is structurally the same, but appears in ribbonlike patterns that do not completely encircle the cells. One example is in

cardiomyocytes Cardiac muscle (also called heart muscle, myocardium, cardiomyocytes and cardiac myocytes) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle tha ...

Proteins

Adherens junctions are composed of the following proteins: * cadherins. The cadherins are a family of transmembrane proteins that form homodimers in a calcium-dependent manner with other cadherin molecules on adjacent cells. * p120 (sometimes called

delta catenin Delta-1-catenin and Delta-2-catenin are members of a subfamily of proteins with ten Armadillo-repeats. Delta-2-catenin is expressed in the brain where it is important for normal cognitive development. Like beta-catenin and gamma-catenin, delta- ...

) binds the juxtamembrane region of the cadherin. *

γ-catenin Plakoglobin, also known as junction plakoglobin or gamma-catenin, is a protein that in humans is encoded by the ''JUP'' gene. Plakoglobin is a member of the catenin protein family and homologous to β-catenin. Plakoglobin is a cytoplasmic compone ...

or gamma-catenin ( plakoglobin) binds the catenin-binding region of the cadherin. * α-catenin or alpha-catenin binds the cadherin indirectly via

β-catenin Catenin beta-1, also known as beta-catenin (β-catenin), is a protein that in humans is encoded by the ''CTNNB1'' gene. Beta-catenin is a dual function protein, involved in regulation and coordination of cell–cell adhesion and gene transcrip ...

or plakoglobin and links the actin cytoskeleton with cadherin. Significant

protein dynamics Proteins are generally thought to adopt unique structures determined by their amino acid sequences. However, proteins are not strictly static objects, but rather populate ensembles of (sometimes similar) conformations. Transitions between these stat ...

is thought to be involved.

Models

Adherens junctions were, for many years, thought to share the characteristic of anchor cells through their cytoplasmic

filaments. Adherens junctions may serve as a regulatory module to maintain the actin

contractile ring In molecular biology, an actomyosin contractile ring is a prominent structure during cytokinesis.Cheffings TH, Burroughs NJ, Balasubramanian MK. (2016). Actomyosin Ring Formation and Tension Generation in Eukaryotic Cytokinesis. Curr Biol. 26(15): ...

with which it is associated in microscopic studies.

References

External links

MBInfo - Adherens Junction

MBInfo - Adherens Junction Assembly
* * {{Authority control Cell anatomy