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Questions and Answers
Selectins are regulated by ______ mediators
Selectins are regulated by ______ mediators
inflammatory
Hemidesmosomes link extracellular laminin in the basement membrane to ______ within epithelial cells
Hemidesmosomes link extracellular laminin in the basement membrane to ______ within epithelial cells
keratins
Integrins are a family of adhesion molecules that are ______ bound heterodimers
Integrins are a family of adhesion molecules that are ______ bound heterodimers
non-covalently
Desmosomes and adherens junctions involve proteins that connect to the ______ cytoskeleton
Desmosomes and adherens junctions involve proteins that connect to the ______ cytoskeleton
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The ______ superfamily includes proteins important for cell adhesion and immune response
The ______ superfamily includes proteins important for cell adhesion and immune response
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Integrins are involved in the attachment of epithelial cells to the ______.
Integrins are involved in the attachment of epithelial cells to the ______.
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In the absence of ligand, integrin dimers adopt a ______ structure.
In the absence of ligand, integrin dimers adopt a ______ structure.
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Talin can activate integrins through ______-out signaling.
Talin can activate integrins through ______-out signaling.
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The extracellular portion of integrins adopts an extended conformation to achieve higher ______ for ligand.
The extracellular portion of integrins adopts an extended conformation to achieve higher ______ for ligand.
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Focal adhesions are specialized structures involved in cell-matrix ______.
Focal adhesions are specialized structures involved in cell-matrix ______.
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Gap junctions function primarily in ______ communication between cells.
Gap junctions function primarily in ______ communication between cells.
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Selectins play a crucial role in mediating ______ response during inflammation.
Selectins play a crucial role in mediating ______ response during inflammation.
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Catenins link cadherins to the ______ network inside the cell.
Catenins link cadherins to the ______ network inside the cell.
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Cadherins are a family of adhesion proteins which mediate Ca2+ dependent ______ adhesion.
Cadherins are a family of adhesion proteins which mediate Ca2+ dependent ______ adhesion.
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Catenins link classical cadherins to the ______ cytoskeleton.
Catenins link classical cadherins to the ______ cytoskeleton.
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Gap junctions enable small molecule transfer including inorganic ions, sugars, and ______.
Gap junctions enable small molecule transfer including inorganic ions, sugars, and ______.
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The T cell receptor is an Ig family ______ molecule.
The T cell receptor is an Ig family ______ molecule.
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Selectins are cell surface carbohydrate binding proteins that are ______ dependent.
Selectins are cell surface carbohydrate binding proteins that are ______ dependent.
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Transient, weak interactions between selectins on endothelial cells and carbohydrate ligands on ______ allow the cells to attach to blood vessel walls.
Transient, weak interactions between selectins on endothelial cells and carbohydrate ligands on ______ allow the cells to attach to blood vessel walls.
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Immunoglobulin superfamily members can be either homophilic or ______ in their adhesion capabilities.
Immunoglobulin superfamily members can be either homophilic or ______ in their adhesion capabilities.
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In the immune response, PECAM is found on platelets and ______ cells.
In the immune response, PECAM is found on platelets and ______ cells.
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The cadherin extracellular domains link together to mediate ______.
The cadherin extracellular domains link together to mediate ______.
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Integrins mediate tight binding and migration into connective ______.
Integrins mediate tight binding and migration into connective ______.
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Cadherins form junctions that are individually low affinity but combine to give strong ______.
Cadherins form junctions that are individually low affinity but combine to give strong ______.
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Tight junctions are important for maintaining ______ integrity in epithelial layers.
Tight junctions are important for maintaining ______ integrity in epithelial layers.
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Gap junctions also facilitate the transfer of ______ signaling molecules between cells.
Gap junctions also facilitate the transfer of ______ signaling molecules between cells.
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Cadherins require ______ for their function, which is crucial for cell adhesion.
Cadherins require ______ for their function, which is crucial for cell adhesion.
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What structural change occurs in integrin dimers after activation by ligand binding?
What structural change occurs in integrin dimers after activation by ligand binding?
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What is the role of talin in the inside-out signaling mechanism of integrin activation?
What is the role of talin in the inside-out signaling mechanism of integrin activation?
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Which of the following describes the function of focal adhesions in motile cells?
Which of the following describes the function of focal adhesions in motile cells?
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Which factor is involved in the activation of integrins in response to chemokine receptor activation?
Which factor is involved in the activation of integrins in response to chemokine receptor activation?
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What effect does ligand binding have on the conformation of integrins?
What effect does ligand binding have on the conformation of integrins?
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What is the primary role of cell adhesion molecules in multicellular organisms?
What is the primary role of cell adhesion molecules in multicellular organisms?
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Which type of junction primarily seals gaps between epithelial cells to maintain permeability?
Which type of junction primarily seals gaps between epithelial cells to maintain permeability?
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What type of adhesion is primarily involved in the transient binding of leukocytes to endothelial cells?
What type of adhesion is primarily involved in the transient binding of leukocytes to endothelial cells?
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Which family of proteins links to the actin cytoskeleton and plays a key role in adherens junctions?
Which family of proteins links to the actin cytoskeleton and plays a key role in adherens junctions?
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Which junction allows the passage of small molecules and ions between the cytoplasm of adjacent cells?
Which junction allows the passage of small molecules and ions between the cytoplasm of adjacent cells?
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What is the primary function of integrins in cell adhesion?
What is the primary function of integrins in cell adhesion?
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Which type of junction provides mechanical strength and resistance to stress in tissues like the skin?
Which type of junction provides mechanical strength and resistance to stress in tissues like the skin?
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What type of signaling occurs at the sites of cell-cell contact formed by cell adhesion molecules?
What type of signaling occurs at the sites of cell-cell contact formed by cell adhesion molecules?
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What role do selectins play in the body during inflammation?
What role do selectins play in the body during inflammation?
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Which of the following statements correctly describes syndecans?
Which of the following statements correctly describes syndecans?
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What is a unique characteristic of hemidesmosomes?
What is a unique characteristic of hemidesmosomes?
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How do integrins contribute to cellular function?
How do integrins contribute to cellular function?
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Which type of adhesion do selectins primarily mediate?
Which type of adhesion do selectins primarily mediate?
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What is the function of plectin and dystonin in hemidesmosomes?
What is the function of plectin and dystonin in hemidesmosomes?
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Which type of cell adhesion is primarily associated with cadherins?
Which type of cell adhesion is primarily associated with cadherins?
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What cellular response increases the expression of E-selectin on vascular endothelial cells?
What cellular response increases the expression of E-selectin on vascular endothelial cells?
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Which statement best describes integrin function?
Which statement best describes integrin function?
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What is the primary role of selectins during an inflammatory response?
What is the primary role of selectins during an inflammatory response?
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What is the role of catenins in relation to cadherins?
What is the role of catenins in relation to cadherins?
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What distinguishes the immunoglobulin superfamily from cadherins?
What distinguishes the immunoglobulin superfamily from cadherins?
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How do cadherins achieve strong attachment despite their individual low affinity?
How do cadherins achieve strong attachment despite their individual low affinity?
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Which type of molecules can gap junctions transfer between cells?
Which type of molecules can gap junctions transfer between cells?
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What is a primary function of cadherins in embryonic development?
What is a primary function of cadherins in embryonic development?
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Which component does L-selectin interact with for lymphocyte homing?
Which component does L-selectin interact with for lymphocyte homing?
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What is indicated by the presence of multiple Ig-family adhesion molecules during immune responses?
What is indicated by the presence of multiple Ig-family adhesion molecules during immune responses?
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What role do tight junctions play in epithelial tissue?
What role do tight junctions play in epithelial tissue?
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Which characteristic is specific to integrins compared to cadherins?
Which characteristic is specific to integrins compared to cadherins?
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Study Notes
Cell Adhesion and Cell Signalling
- Multicellular organisms rely on cell adhesion to each other and the extracellular matrix (ECM) for tissue formation.
- Some adhesive interactions are stable, like those between muscle cells and connective tissue in tendons for force transmission, or skin epithelial cells to prevent abrasion.
- Other cellular adhesions are transient, such as leukocytes binding to endothelial cells for extravasation into tissues, or cell attachment to the ECM during migration.
Cell Junctions
- Cell-cell junctions (adherens junctions, desmosomes), and cell-matrix adhesions (actin-linked, or hemidesmosomes) connect to the cytoskeleton and transmit physical forces.
- Tight junctions (septate junctions) seal gaps between epithelial cells, controlling permeability.
- Gap junctions allow small molecules and ions to pass between cells, facilitating signal transduction.
Cellular Adhesion Molecules
- Cadherins link cells to cells and mediate Ca2+ dependent homophilic adhesion.
- Integrins link cells to the extracellular matrix (ECM) and mediate adhesion of cells to the ECM.
- Selectins mediate interactions between cells, particularly important in immune functions.
- Immunoglobulin (Ig) superfamily members exhibit Ca2+ independent adhesion, playing important roles in various cell interactions.
Cell-Cell Adhesion at a Synapse
- Synapse formation requires multiple adhesion molecules to join pre- and post-synaptic membranes.
- This process anchors components of signalling machinery firmly, thereby localising neurotransmitter actions.
Selectins
- Selectins are cell-surface carbohydrate-binding proteins that bind to mucin-type glycoproteins.
- Their function is Ca2+-dependent and is essential for binding to white blood cells, platelets, and endothelial cells.
Cell Adhesion Molecules in Lymph Nodes
- Lymphocytes bind to vascular endothelium in lymph nodes via interactions between L-selectin and vascular addressins.
Cell Adhesion Molecules and Neutrophil Recruitment
- Selectin-mediated adhesion is weak, enabling neutrophils to roll along blood vessels.
- Transient, weak interactions allow cells to attach to blood vessel walls.
- Other adhesion molecules regulate tight binding and migration into infected tissue.
Regulation of Selectins
- Selectins are responsive to inflammatory mediators, like TNFα, CXCL8, leukotriene LTB4, histamine, and thrombin.
- These mediators induce upregulation of E-selectins on vascular endothelial cells, facilitating neutrophil extravasation.
Syndecans
- Syndecans are cell-surface proteoglycans that are expressed on many cell types, mediating cell adhesion to the extracellular matrix and binding growth factors like FGF.
Desmosomes
- Desmosomes are cell-cell junctions. They are formed by non-classical cadherin proteins and intermediate filaments.
Hemidesmosomes
- Hemidesmosomes are anchoring junctions. They link cells to the basal lamina via integrins that connect to keratins within epithelial cells.
Integrin Mediated Adhesions
- Integrins mediate various cell-cell and cell-matrix adhesions through different types of adhesion structures (focal adhesions and podosomes).
Integrin Activation
- Integrins can exist in active or inactive states, controlled by outside-in or inside-out signalling.
Integrin Pairs
- Integrins are heterodimeric transmembrane proteins playing vital roles in cell-cell and cell-matrix adhesion. They exhibit variability across different cell types/tissues.
Integrin Ligands
- Various extracellular matrix proteins serve as ligands for integrins, influencing cell adhesion and migration.
Integrins in Cell-Cell Adhesion
- Integrins can bind to other cellular adhesion molecules like those in the Ig family, potentially strengthening the interaction.
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Description
This quiz explores the concepts of cell adhesion, cell junctions, and cellular adhesion molecules in multicellular organisms. It covers the significance of stable and transient adhesive interactions and the role of junctions in maintaining tissue integrity and regulating permeability. Test your understanding of how these mechanisms contribute to cellular communication and tissue formation.
