The main difference between cadherins and integrins is that cadherin is a cell adhesion molecule that mediates cell-to-cell adhesion, whereas integrin is a cell adhesion molecule that mediates cell-to-extracellular matrix adhesion.
Cell adhesion molecules are proteins present on the surface of cells. They play an important role in cell adhesion. They also play a major role in cellular processes like tissue development, immune response, wound healing, and metastasis. Cadherins, integrins, and selectins are a few examples of cell adhesion molecules.
Key Areas Covered
1. What are Cadherins
– Definition, Types, Functions
2. What are Integrins
– Definition, Types, Functions
3. Difference Between Cadherins and Integrins
– Comparison of Key Differences
Key Terms
Cadherins, Integrins
What are Cadherins
Cadherins are a group of proteins that help the cells to stick together. They are a type of transmembrane protein. They depend on the Calcium ions (Ca2+) ions to function. Moreover, cadherins are synthesized as polypeptides. They later get modified to become the proteins that mediate cell-to-cell adhesion and recognition. In addition, their polypeptide chain is about 720-750 amino acids long.
Furthermore, a cadherin has three distinguishable parts: a small C-terminal cytoplasmic component, a transmembrane component, and the remaining part outside the cell. This extracellular domain binds to other cadherins on adjacent cells while the cytoplasmic domains interact with the cell’s cytoskeleton, anchoring the protein to the cell membrane. The interactions between the cadherins and other cells are strong and very stable. It is helpful in the maintenance of tissue integrity. It is also useful for the formation of organized tissue structures during development.
Types of Cadherins
Furthermore, different types of cadherins are present in different tissues. There are four groups of cadherins in vertebrates. They are classical cadherins, desmoglein, desmocollin (which are desmosomal cadherins), protocadherins, and unconventional cadherins.
In addition, two types of cellular junctions rely on cadherins: adherens junctions and desmosomes. Adherens junctions have a strip of cadherin molecules that connect the membranes of the epithelial cells. Desmosomes, on the other hand, are structures inside the membrane of the cells that use cadherins, desmoglein, and desmocollin, to penetrate through the membranes and form interlocking networks that connect the cells together.
Moreover, the functions of cadherins include mediating cell-to-cell adhesion, forming adherens junctions between adjacent cells, and involvement in tissue development and morphogenesis.
What are Integrins
Integrins are cell adhesion molecules that mediate the cell to the extracellular matrix. They are transmembrane receptors. Furthermore, integrins are made up of two subunits; alpha and beta subunits, each of which has a large extracellular domain that binds to a specific extracellular matrix like collagen or fibronectin. Besides, this binding of integrins is necessary for cell attachment, migration, and the regulation of intracellular signalling pathways. These integrin subunits span the cell membrane. They also have short cytoplasmic domains of 40-70 amino acids. The beta-4 subunit is an exception and has a cytoplasmic domain of 1088 amino acids. Moreover, the molecular mass of integrin subunits can vary between 90kDa to 160 kDa.
Based on their structure and function, integrins can be classified into four subfamilies; the are collagen-binding integrins, laminin-binding integrins, RGD-binding integrins, and leukocyte-specific integrins. In addition, there are some other families that do not fall into any of the above four categories. In fact, Alpha4beta7 is an example of such an integrin.
One main function of integrins is mediating cell migration, which is essential for processes like wound healing, embryo development, and cancer metastasis. Moreover, another function of integrins is to regulate cell proliferation and survival. Integrins also mediate interactions between immune cells and the ECM during inflammation and tissue repair. In addition, they are involved in leukocyte trafficking, extravasation, migration of immune cells, and the formation of immune synapses.
Difference Between Cadherins and Integrins
Definition
Cadherin is a cell adhesion molecule that mediates cell-to-cell adhesion, whereas integrin is a cell adhesion molecule that mediates cell-to-extracellular matrix adhesion.
Types
Some types of cadherins include classical cadherins, desmoglein and desmocollin, protocadherins, and unconventional cadherins, while types of integrins include collagen-binding integrins, laminin-binding integrins, RGD-binding integrins, and leukocyte-specific integrins.
Functions
The functions of cadherins include mediating cell-to-cell adhesion, forming adherens junctions between adjacent cells, and involvement in tissue development and morphogenesis, whereas the functions of integrins include mediating cell migrations, regulating cell proliferation and survival, and involvement in tissue development and morphogenesis.
Conclusion
In brief, cell adhesion molecules are proteins present on the surface of the cells. Both molecules play an important role in cell adhesion. Cadherins and integrins are two types of cell adhesion molecules. The main difference between cadherins and integrins is that cadherin is a cell adhesion molecule that mediates cell-to-cell adhesion, whereas integrin is a cell adhesion molecule that mediates cell-to-extracellular matrix adhesion.
Reference:
1. “Integrins.” Molecular Biology of the Cell. 4th edition. National Library of Medicine.
2. “Three Functions of Cadherins in Cell Adhesion” National Library of Medicine.
Image Courtesy:
1. “Integrins promote axonal regeneration after injury of the nervous system – Biological Reviews – doi 10.1111-brv.12398” By Nieuwenhuis, B., Haenzi, B., Andrews, M. R., Verhaagen, J. and Fawcett, J. W. (2018), Integrins promote axonal regeneration after injury of the nervous system. Biol Rev. doi:10.1111/brv.12398 (CC BY 4.0) via Commons Wikimedia
2. “Protocadherins image2” By TelmaGL – Handmade (CC0) via Commons Wikimedia
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