Desmosome
Encyclopedia
A desmosome also known as macula adherens (plural: maculae adherentes) (Latin for adhering spot), is a cell
structure specialized for cell-to-cell adhesion
. A type of junctional complex
, they are localized spot-like adhesions randomly arranged on the lateral sides of plasma membranes.
Desmosomes help to resist shearing forces and are found in simple
and stratified squamous epithelium
. The intercellular space is very wide (about 30 nm). Desmosomes are also found in muscle tissue where they bind muscle cells to one another.
cytoskeletal
filaments.
The cell adhesion proteins of the desmosome, desmoglein and desmocollin, are members of the cadherin
family of cell adhesion molecules. They are transmembrane protein
s that bridge the space between adjacent epithelial cells by way of homophilic binding of their extracellular domains to other desmosomal cadherins on the adjacent cell. Both have five extracellular domains, and have calcium-binding motifs.
The extracellular domain of the desmosome is called the Extracellular Core Domain (ECD) or the Desmoglea, and is bisected by an electron-dense midline where the desmoglein and desmocollin proteins bind to each other. These proteins can bind in a W, S, or λ manner.
On the cytoplasmic side of the plasma membrane, there are two dense structures called the Outer Dense Plaque (ODP) and the Inner Dense Plaque (IDP). These are spanned by the Desmoplakin
protein. The Outer Dense Plaque is where the cytoplasmic domains of the cadherins attach to desmoplakin
via plakoglobin
and plakophillin. The Inner Dense Plaque is where desmoplakin
attaches to the intermediate filaments of the cell.
, Desmoglein2, Desmocollin2 and Plakoglobin
. It often afflicts (although not exclusive to) young male athletes. The current incidence within the population is accepted as 1/10,000 however it is thought that 1/200 may have a mutation that may predispose to ARVC.
are not functioning correctly, layers of the skin can pull apart and allow abnormal movements of fluid within the skin, resulting in blisters and other tissue damage. Blistering diseases such as Pemphigus vulgaris
and Pemphigus foliaceus
are autoimmune diseases in which auto-antibodies target the proteins desmoglein 3
and desmoglein 1
respectively. The symptoms of the diseases are caused by the subsequent disruption to the desmosome-keratin
filament complex leading to a breakdown in cell adhesion.
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
structure specialized for cell-to-cell adhesion
Cell adhesion
Cellular adhesion is the binding of a cell to a surface, extracellular matrix or another cell using cell adhesion molecules such as selectins, integrins, and cadherins. Correct cellular adhesion is essential in maintaining multicellular structure...
. A type of junctional complex
Cell junction
A cell junction is a type of structure that exists within the tissue of a some multicellular organism . Cell junctions consist of protein complexes and provide contact between neighbouring cells or between a cell and the extracellular matrix...
, they are localized spot-like adhesions randomly arranged on the lateral sides of plasma membranes.
Desmosomes help to resist shearing forces and are found in simple
Simple squamous epithelium
A simple squamous epithelium is a single layer of flat cells in contact with the basal lamina of the epithelium. This type of epithelium is often permeable and occurs where small molecules pass quickly through membranes via filtration or diffusion...
and stratified squamous epithelium
Stratified squamous epithelium
A stratified squamous epithelium consists of squamous epithelial cells arranged in layers upon a basement membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity...
. The intercellular space is very wide (about 30 nm). Desmosomes are also found in muscle tissue where they bind muscle cells to one another.
Structure
Desmosomes are molecular complexes of cell adhesion proteins and linking proteins that attach the cell surface adhesion proteins to intracellular keratinKeratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
cytoskeletal
Cytoskeleton
The cytoskeleton is a cellular "scaffolding" or "skeleton" contained within a cell's cytoplasm and is made out of protein. The cytoskeleton is present in all cells; it was once thought to be unique to eukaryotes, but recent research has identified the prokaryotic cytoskeleton...
filaments.
The cell adhesion proteins of the desmosome, desmoglein and desmocollin, are members of the cadherin
Cadherin
Cadherins are a class of type-1 transmembrane proteins. They play important roles in cell adhesion, ensuring that cells within tissues are bound together. They are dependent on calcium ions to function, hence their name.The cadherin superfamily includes cadherins, protocadherins, desmogleins, and...
family of cell adhesion molecules. They are transmembrane protein
Transmembrane protein
A transmembrane protein is a protein that goes from one side of a membrane through to the other side of the membrane. Many TPs function as gateways or "loading docks" to deny or permit the transport of specific substances across the biological membrane, to get into the cell, or out of the cell as...
s that bridge the space between adjacent epithelial cells by way of homophilic binding of their extracellular domains to other desmosomal cadherins on the adjacent cell. Both have five extracellular domains, and have calcium-binding motifs.
The extracellular domain of the desmosome is called the Extracellular Core Domain (ECD) or the Desmoglea, and is bisected by an electron-dense midline where the desmoglein and desmocollin proteins bind to each other. These proteins can bind in a W, S, or λ manner.
On the cytoplasmic side of the plasma membrane, there are two dense structures called the Outer Dense Plaque (ODP) and the Inner Dense Plaque (IDP). These are spanned by the Desmoplakin
Desmoplakin
Desmoplakin is a protein associated with desmosomes.Desmoplakin is a protein that in humans is encoded by the DSP gene. The C-terminus of desmoplakin binds with intermediate filaments. These are further sub divided to three homologous Plakin repeat domains . In the mid-region of desmoplakin, a...
protein. The Outer Dense Plaque is where the cytoplasmic domains of the cadherins attach to desmoplakin
Desmoplakin
Desmoplakin is a protein associated with desmosomes.Desmoplakin is a protein that in humans is encoded by the DSP gene. The C-terminus of desmoplakin binds with intermediate filaments. These are further sub divided to three homologous Plakin repeat domains . In the mid-region of desmoplakin, a...
via plakoglobin
Plakoglobin
Junction plakoglobin, also known as gamma-catenin or JUP, is a protein that in humans is encoded by the JUP gene.- Function :...
and plakophillin. The Inner Dense Plaque is where desmoplakin
Desmoplakin
Desmoplakin is a protein associated with desmosomes.Desmoplakin is a protein that in humans is encoded by the DSP gene. The C-terminus of desmoplakin binds with intermediate filaments. These are further sub divided to three homologous Plakin repeat domains . In the mid-region of desmoplakin, a...
attaches to the intermediate filaments of the cell.
Arrhythmogenic right ventricular cardiomyopathy
Mutations within the desmosome are the main cause of Arrhythmogenic right ventricular cardiomyopathy (ARVC). It is a life threatening disease with the molecular underpinnings being the desmosomal constituents (in rank of highest mutation rates) Plakophilin2, DesmoplakinDesmoplakin
Desmoplakin is a protein associated with desmosomes.Desmoplakin is a protein that in humans is encoded by the DSP gene. The C-terminus of desmoplakin binds with intermediate filaments. These are further sub divided to three homologous Plakin repeat domains . In the mid-region of desmoplakin, a...
, Desmoglein2, Desmocollin2 and Plakoglobin
Plakoglobin
Junction plakoglobin, also known as gamma-catenin or JUP, is a protein that in humans is encoded by the JUP gene.- Function :...
. It often afflicts (although not exclusive to) young male athletes. The current incidence within the population is accepted as 1/10,000 however it is thought that 1/200 may have a mutation that may predispose to ARVC.
Blistering diseases
If the connecting adjacent epithelial cells of the skinSkin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
are not functioning correctly, layers of the skin can pull apart and allow abnormal movements of fluid within the skin, resulting in blisters and other tissue damage. Blistering diseases such as Pemphigus vulgaris
Pemphigus vulgaris
Pemphigus vulgaris is a chronic blistering skin disease with skin lesions that are rarely pruritic, but which are often painful.-Pathophysiology:...
and Pemphigus foliaceus
Pemphigus foliaceus
Pemphigus foliaceus is an autoimmune blistering disease of the skin and mucous membranes with characteristic lesions that are scaly, crusted erosions, often on an erythematous base...
are autoimmune diseases in which auto-antibodies target the proteins desmoglein 3
Desmoglein 3
Desmoglein-3 is a protein that in humans is encoded by the DSG3 gene.-Interactions:Desmoglein 3 has been shown to interact with PKP3.-Further reading:...
and desmoglein 1
Desmoglein 1
Desmoglein 1 is a protein that in humans is encoded by the DSG1 gene.-Interactions:Desmoglein 1 has been shown to interact with PKP3 and PKP2.-Further reading:...
respectively. The symptoms of the diseases are caused by the subsequent disruption to the desmosome-keratin
Intermediate filament
Intermediate filaments are a family of related proteins that share common structural and sequence features. Intermediate filaments have an average diameter of 10 nanometers, which is between that of 7 nm actin , and that of 25 nm microtubules, although they were initially designated...
filament complex leading to a breakdown in cell adhesion.