Biology: Anchoring Junctions

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Questions and Answers

What type of proteins do desmoglein and desmocollin belong to?

Cadherin family (correct)

Plaque proteins

Anchor proteins

Intermediate filaments

What do desmoglein and desmocollin bind to via anchor proteins?

Microtubules

Intermediate filaments (correct)

Cytoplasmic plaque

Cell membrane

What is the function of desmoglein and desmocollin in desmosomes?

To regulate gene expression

To provide cell signaling

To link adjacent cells together (correct)

To provide mechanical strength

What is the effect of antibodies against desmosomal cadherins in Pemphigus?

Disruption of desmosomes Signup and view all the answers

Which of the following tissues are desmosomes most abundant in?

Epidermis of the skin and heart muscle Signup and view all the answers

What is the role of desmosomes in tissues?

To give mechanical strength Signup and view all the answers

What is the name of the autoimmune disease that affects desmosomal cadherins?

Pemphigus Signup and view all the answers

What is the function of the cytoplasmic plaque in desmosomes?

To provide attachment sites for intermediate filaments Signup and view all the answers

What is the role of desmosomes in the development of certain diseases?

They are involved in the formation of cataract and heart malformations Signup and view all the answers

What is the function of anchoring junctions?

To provide mechanical strength and stability to cells Signup and view all the answers

What is the structure of hemidesmosomes?

They have a single dense plaque on the cytoplasmic surface Signup and view all the answers

What is the function of integrins in hemidesmosomes?

To bind to laminin protein in the basal lamina Signup and view all the answers

What is the consequence of mutations in plectin?

Skin blisters Signup and view all the answers

What is the function of focal adhesions?

To bind cells to the extracellular matrix Signup and view all the answers

What is the type of adhesion protein involved in hemidesmosomes?

Integrin Signup and view all the answers

What is the type of cytoskeletal element involved in hemidesmosomes?

Intermediate filaments Signup and view all the answers

What is the result of the loss of Desmoglein 3 in skin cells?

Severe blistering of the skin Signup and view all the answers

What type of intermediate filaments are found in heart and muscle cells?

Desmin filaments Signup and view all the answers

What type of junction is involved in cell-cell adhesion?

Desmosomes Signup and view all the answers

What is the main function of hemidesmosomes?

Cell-matrix adhesion Signup and view all the answers

What is the name of the protein that attaches to keratin intermediate filaments in hemidesmosomes?

Plectin Signup and view all the answers

What is the name of the disease caused by autoantibodies attacking type XVII collagen?

Bullous pemphigoid Signup and view all the answers

What is the result of mutations in plectin?

Skin blisters Signup and view all the answers

What type of collagen is involved in hemidesmosomes?

Type XVII collagen Signup and view all the answers

What is the primary function of desmosomes in tissues?

To provide mechanical binding and strength Signup and view all the answers

What type of proteins are desmoglein and desmocollin part of?

Cadherin family Signup and view all the answers

Which of the following structures is not part of a desmosome?

Golgi apparatus Signup and view all the answers

What is the consequence of antibodies binding to desmosomal cadherins in Pemphigus?

Disruption of desmosomes and skin epithelial cell detachment Signup and view all the answers

Which of the following proteins is not part of the cytoplasmic plaque in desmosomes?

Integrin Signup and view all the answers

What is the role of desmoglein and desmocollin in desmosomes?

To link adjacent cells together Signup and view all the answers

What is the characteristic of tissues where desmosomes are most abundant?

Exposed to mechanical stress Signup and view all the answers

What is the function of the plaque proteins in desmosomes?

To link the cadherins to intermediate filaments Signup and view all the answers

What is the result of the loss of Desmoglein 3 in skin cells?

Severe blistering of the skin with leakage of body fluids Signup and view all the answers

What type of intermediate filaments are involved in desmosomes?

Keratin filaments Signup and view all the answers

What is the function of anchoring junctions?

To provide mechanical strength to tissues Signup and view all the answers

What is the name of the disease caused by autoantibodies attacking Desmoglein 3?

Pemphigus vulgaris Signup and view all the answers

What type of anchoring junction is involved in cell-matrix adhesion?

Hemidesmosomes Signup and view all the answers

What is the function of integrins in hemidesmosomes?

To bind to laminin in the basal lamina Signup and view all the answers

What is the result of mutations in plectin?

Skin blisters associated with late-onset muscular dystrophy Signup and view all the answers

What is the function of anchoring junctions in epithelial cells?

To provide mechanical strength to tissues Signup and view all the answers

Which of the following is NOT a type of anchoring junction?

Gap Junctions Signup and view all the answers

What is the function of integrins in hemidesmosomes?

To bind to laminin protein in the basal lamina Signup and view all the answers

Which of the following is a result of mutations in plectin?

Skin blisters Signup and view all the answers

What is the main function of hemidesmosomes?

To anchor loops of intermediate filaments Signup and view all the answers

What is the name of the protein that binds to keratin intermediate filaments in hemidesmosomes?

Plectin Signup and view all the answers

Which of the following is an example of an autoimmune disease that affects hemidesmosomes?

Bullous pemphigoid Signup and view all the answers

What is the type of cytoskeletal element involved in hemidesmosomes?

Intermediate filaments Signup and view all the answers

What is the consequence of autoantibodies attacking type XVII collagen?

Blistering skin disease Signup and view all the answers

What is the primary function of desmoglein and desmocollin in cell-cell adhesion?

To link adjacent cells together through desmosomes Signup and view all the answers

What is the consequence of desmoglein and desmocollin dysfunction in the epidermis?

Disruption of desmosomes leading to skin blistering Signup and view all the answers

Which of the following proteins is NOT directly involved in desmosome formation?

Integrin Signup and view all the answers

What is the characteristic of tissues where desmosomes are most abundant?

Exposure to mechanical stress Signup and view all the answers

What is the role of the cytoplasmic plaque in desmosomes?

To anchor intermediate filaments to the cell membrane Signup and view all the answers

Which of the following is a consequence of antibodies binding to desmosomal cadherins in Pemphigus?

Disruption of desmosomes leading to skin blistering Signup and view all the answers

What is the function of desmoglein and desmocollin in heart muscle tissue?

To provide mechanical strength to the tissue Signup and view all the answers

Which of the following proteins is involved in the formation of desmosomes in the epidermis?

Desmoplakin Signup and view all the answers

What is the primary function of desmoglein 3 in epithelial cells?

To form a strong attachment to adjacent cells Signup and view all the answers

What is the consequence of the loss of desmoglein 3 in skin cells?

Severe blistering of the skin with leakage of body fluids Signup and view all the answers

Which of the following best describes the function of desmoglein and desmocollin?

To form a strong attachment to adjacent cells and maintain tissue integrity Signup and view all the answers

What is the characteristic of the autoimmune disease that affects desmoglein 3?

It results in severe blistering of the skin with leakage of body fluids Signup and view all the answers

What is the role of desmoglein and desmocollin in desmosomes?

To form a strong attachment to adjacent cells and maintain tissue integrity Signup and view all the answers

What is the consequence of autoantibodies attacking desmoglein 3?

Severe blistering of the skin with leakage of body fluids Signup and view all the answers

What is the characteristic of the skin disease caused by autoantibodies attacking desmoglein 3?

It results in severe blistering of the skin with leakage of body fluids Signup and view all the answers

What is the role of desmoglein 3 in maintaining the integrity of epithelial tissues?

To form a strong attachment to adjacent cells Signup and view all the answers

What is the primary function of Desmoglein and Desmocollin in desmosomes?

To facilitate cell-cell adhesion and maintain tissue integrity Signup and view all the answers

What is the consequence of autoantibodies binding to Desmoglein and Desmocollin in Pemphigus?

Disruption of cell-cell adhesion and blistering of skin Signup and view all the answers

Which of the following is a characteristic feature of Desmoglein and Desmocollin?

Transmembrane proteins with a single transmembrane domain Signup and view all the answers

What is the result of the loss of Desmoglein 3 in skin cells?

Disrupted cell-cell adhesion and blistering of skin Signup and view all the answers

Which of the following is NOT a function of Desmoglein and Desmocollin?

Cell migration and invasion Signup and view all the answers

What is the type of protein that Desmoglein and Desmocollin belong to?

Adhesion proteins Signup and view all the answers

What is the consequence of mutations in Desmoglein and Desmocollin?

Disrupted cell-cell adhesion and blistering of skin Signup and view all the answers

What is the role of Desmoglein and Desmocollin in heart tissue?

To facilitate cell-cell adhesion and maintain tissue integrity Signup and view all the answers

Study Notes

Anchoring Junctions

Anchoring junctions can be subclassified according to the cytoskeletal element that is involved.
There are two types of anchoring junctions: actin filament attachment sites and intermediate filament attachment sites.

Actin Filament Attachment Sites

Cell-cell junctions: adherens junctions
Cell-matrix junctions: focal adhesions

Intermediate Filament Attachment Sites

Cell-cell junctions: desmosomes
Cell-matrix junctions: hemidesmosomes

Desmosomes

Strongest points of cell adhesion that provide mechanical binding
Most abundant in tissues that are exposed to mechanical stress (epidermis of the skin, heart muscle)
Cell to cell binding depends on cadherin family of proteins called desmoglein and desmocollin
Contain plaque-shaped structures on the cytoplasmic face of the junction which provide attachment sites for intermediate filaments
Plaque proteins are: plakoglobins, desmoplakins, plakophilins
Desmosomes are found in many tissues, especially abundant in skin (epidermis), heart muscle, and the neck of the uterus
Importance of desmosome junctions is demonstrated by some of the skin autoimmune diseases, such as pemphigus

Hemidesmosomes

Resemble desmosomes morphologically
Cell uses hemidesmosomes to attach to the basal lamina
Have only a single dense plaque on the cytoplasmic surface of the hemidesmosome (hemi=half) that anchors loops of intermediate filaments
Integrin (α6β4) and type XVII collagen (also called BPAG2) attach to the basal lamina
In a blistering skin disease called bullous pemphigoid, autoantibodies attack type XVII collagen
Mutations in plectin cause skin blisters associated with late-onset muscular dystrophy

Focal Adhesions

Bind the cells to the extracellular matrix
Cell to matrix adhesion proteins; integrins responsible for the binding to the matrix
Cytoplasmic domain of the integrin binds indirectly to actin filaments
Integrin's extracellular domains bind to components of extracellular matrix, while the cytoplasmic tail of the β subunit binds indirectly to actin

Anchoring Junctions

Anchoring junctions can be subclassified according to the cytoskeletal element that is involved.
There are two types of anchoring junctions: actin filament attachment sites and intermediate filament attachment sites.

Actin Filament Attachment Sites

Cell-cell junctions: adherens junctions
Cell-matrix junctions: focal adhesions

Intermediate Filament Attachment Sites

Cell-cell junctions: desmosomes
Cell-matrix junctions: hemidesmosomes

Desmosomes

Strongest points of cell adhesion that provide mechanical binding
Most abundant in tissues that are exposed to mechanical stress (epidermis of the skin, heart muscle)
Cell to cell binding depends on cadherin family of proteins called desmoglein and desmocollin
Contain plaque-shaped structures on the cytoplasmic face of the junction which provide attachment sites for intermediate filaments
Plaque proteins are: plakoglobins, desmoplakins, plakophilins
Desmosomes are found in many tissues, especially abundant in skin (epidermis), heart muscle, and the neck of the uterus
Importance of desmosome junctions is demonstrated by some of the skin autoimmune diseases, such as pemphigus

Hemidesmosomes

Resemble desmosomes morphologically
Cell uses hemidesmosomes to attach to the basal lamina
Have only a single dense plaque on the cytoplasmic surface of the hemidesmosome (hemi=half) that anchors loops of intermediate filaments
Integrin (α6β4) and type XVII collagen (also called BPAG2) attach to the basal lamina
In a blistering skin disease called bullous pemphigoid, autoantibodies attack type XVII collagen
Mutations in plectin cause skin blisters associated with late-onset muscular dystrophy

Focal Adhesions

Bind the cells to the extracellular matrix
Cell to matrix adhesion proteins; integrins responsible for the binding to the matrix
Cytoplasmic domain of the integrin binds indirectly to actin filaments
Integrin's extracellular domains bind to components of extracellular matrix, while the cytoplasmic tail of the β subunit binds indirectly to actin

Anchoring Junctions

Anchoring junctions can be subclassified according to the cytoskeletal element that is involved.
There are two types of anchoring junctions: actin filament attachment sites and intermediate filament attachment sites.

Actin Filament Attachment Sites

Cell-cell junctions: adherens junctions
Cell-matrix junctions: focal adhesions

Intermediate Filament Attachment Sites

Cell-cell junctions: desmosomes
Cell-matrix junctions: hemidesmosomes

Desmosomes

Strongest points of cell adhesion that provide mechanical binding
Most abundant in tissues that are exposed to mechanical stress (epidermis of the skin, heart muscle)
Cell to cell binding depends on cadherin family of proteins called desmoglein and desmocollin
Contain plaque-shaped structures on the cytoplasmic face of the junction which provide attachment sites for intermediate filaments
Plaque proteins are: plakoglobins, desmoplakins, plakophilins
Desmosomes are found in many tissues, especially abundant in skin (epidermis), heart muscle, and the neck of the uterus
Importance of desmosome junctions is demonstrated by some of the skin autoimmune diseases, such as pemphigus

Hemidesmosomes

Resemble desmosomes morphologically
Cell uses hemidesmosomes to attach to the basal lamina
Have only a single dense plaque on the cytoplasmic surface of the hemidesmosome (hemi=half) that anchors loops of intermediate filaments
Integrin (α6β4) and type XVII collagen (also called BPAG2) attach to the basal lamina
In a blistering skin disease called bullous pemphigoid, autoantibodies attack type XVII collagen
Mutations in plectin cause skin blisters associated with late-onset muscular dystrophy

Focal Adhesions

Bind the cells to the extracellular matrix
Cell to matrix adhesion proteins; integrins responsible for the binding to the matrix
Cytoplasmic domain of the integrin binds indirectly to actin filaments
Integrin's extracellular domains bind to components of extracellular matrix, while the cytoplasmic tail of the β subunit binds indirectly to actin

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Description

Learn about the different types of anchoring junctions, including actin filament and intermediate filament attachment sites, and their role in cell-cell and cell-matrix interactions.