cell-cell junction

Definition

Target type: cellularcomponent

A cell junction that forms a connection between two or more cells of an organism; excludes direct cytoplasmic intercellular bridges, such as ring canals in insects. [GOC:aruk, GOC:bc, GOC:dgh, GOC:hb, GOC:mah, PMID:21422226, PMID:28096264]

Cell-cell junctions are specialized structures that mediate contact and communication between adjacent cells. They are essential for tissue integrity, organ development, and physiological function. They are diverse in structure and function, but they all share the common feature of mediating cell-to-cell adhesion.

Here is a detailed description of the cellular components of cell-cell junctions:

**1. Adherens Junctions (AJs):**
* **Proteins:** Cadherins (e.g., E-cadherin, N-cadherin, P-cadherin), catenins (α, β, γ), vinculin, α-actinin.
* **Structure:** Transmembrane cadherin proteins interact with cadherins on adjacent cells, forming a strong adhesive link. These links are connected to the actin cytoskeleton through catenins and other adaptor proteins.
* **Function:** AJs provide strong cell-cell adhesion and contribute to tissue morphogenesis, cell polarity, and cell signaling. They also regulate cell migration and tissue remodeling.

**2. Desmosomes:**
* **Proteins:** Desmogleins, desmocollins, plakoglobin, plakophilin, desmoplakin.
* **Structure:** Desmosomes are button-like structures that connect the intermediate filament cytoskeletons of adjacent cells. Transmembrane proteins desmogleins and desmocollins bind to each other across the cell-cell gap, forming a strong adhesive junction. These proteins are linked to the intermediate filaments by plakoglobin, plakophilin, and desmoplakin.
* **Function:** Desmosomes provide mechanical strength and resilience to tissues, allowing them to withstand stretching and shear forces. They are particularly abundant in tissues subjected to mechanical stress, such as skin, heart, and muscle.

**3. Tight Junctions (TJs):**
* **Proteins:** Occludin, claudins, ZO proteins (ZO-1, ZO-2, ZO-3).
* **Structure:** TJs are located at the apical end of epithelial cells and form a continuous, belt-like seal that encircles the cell. They are composed of transmembrane proteins, primarily claudins and occludin, which interact with each other and with cytoskeletal proteins on the intracellular side.
* **Function:** TJs act as a barrier to the passage of molecules and ions between cells, maintaining the integrity of epithelial barriers. They regulate the paracellular permeability, contributing to tissue homeostasis and fluid balance.

**4. Gap Junctions:**
* **Proteins:** Connexins.
* **Structure:** Gap junctions are channels that allow direct communication between the cytoplasm of adjacent cells. They are formed by connexins, which assemble into hexameric structures called connexons. Two connexons from neighboring cells dock together to form a channel that allows the passage of small molecules and ions.
* **Function:** Gap junctions facilitate rapid intercellular communication, allowing cells to coordinate their activities. They play essential roles in cell synchronization, development, and tissue function.

**5. Adherens Junctions (AJs):**
* **Proteins:** Cadherins (e.g., E-cadherin, N-cadherin, P-cadherin), catenins (α, β, γ), vinculin, α-actinin.
* **Structure:** Transmembrane cadherin proteins interact with cadherins on adjacent cells, forming a strong adhesive link. These links are connected to the actin cytoskeleton through catenins and other adaptor proteins.
* **Function:** AJs provide strong cell-cell adhesion and contribute to tissue morphogenesis, cell polarity, and cell signaling. They also regulate cell migration and tissue remodeling.

In summary, cell-cell junctions are complex structures that mediate diverse cellular interactions, including adhesion, communication, and barrier formation. They are essential for maintaining tissue integrity, organ function, and organismal development.'
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Proteins (45)

Compounds (1,748)