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18 Cards in this Set
- Front
- Back
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What are the 3 approaches by which cells selectively adhere? |
1. Homophilic binding of cell adhesion molecules. 2. Heterophilic binding of cell adhesion molecules 3. Cell adhesion via extracellular linker molecules. |
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Ho do cells selectively adhere to form organised tissues? |
Interactions mediated by cell adhesion molecules - CAMs called cadherins |
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Example of different cadherins. |
Epidermial and neural cells. Epidermial cells express e-cadherins Neural cells express n-cadherins Cells expressing n-cadherins come together in terms of anchoring junctions. same with e-cadherins. |
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CAMs/ cadherins |
There are different CAM molecules expressed on the surface of different cells. Enabling cell sorting and specific cell to cell adhesion. |
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Different cadherins expressed by Different cells. |
E cadherins N cadherins P cadherins = placenta |
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Level of cadherin expressed |
This can also effect specificity of cell adhesion. |
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What does it mean for CAMs to be calcium dependent? |
Calcium binds to specific sites om the cadherin molecule, which affects the stricture of it. Goes from flopy state to rigid state. This brings cadherin dimers in close proximity to cadherin transmembrane protein on another cell allowing them to interact. |
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What is physiological Importance of cadherins? |
In lab EDTA used to remove calcium. Cell to cell adhesion is very important for cell tissue as they are prone to high mechanical stress. This due to strong adherence cadherins provide. Lack of this can result in ARVC [mutation of desmosomal cadherins]. |
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Autoimmune disease - blistering |
Antibodies attack desmosome cadherins. Skin had multiple layers of epithelial cells in which desmosome cadherins are mediating cell to cell adhesion/interaction. During to antibodies these layers separate = blistering |
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What are the 5 main classes of adhering? |
1. Cadherins - desmosomes Heterophilic 2. Integrins - hemidesmosomes [cell-ECM) 3. Ig superfamily [igCAMs] Heterophilic 4. Selectins 5. Mucin-like CAMs |
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What is the common pfeature of the adhering. |
They all have to pads the memberane. Intracellular domain -> interacts with cytoskeleton Extracellular domain-> mediates cell adhesion |
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Heterophilic binding |
Different cell adhesion molecules binding = mediating selectivity. Selectin Integrin |
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Cell adhesion via extracellular linker protein molecule. |
2 cells and receptor with linker protein |
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What are ig CAM adhesion |
Heterophilic This may be within same cell type or different cell type. |
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What are selectins |
Carbohydrates binding proteins. Mediate weeks transient interaction in terms of cell-cell adhesion |
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What adherins are calcium dependent? |
Selectin Integrin Cadherin |
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Selectin - inflammation |
Endothelial cells express selectins. Selectins bind glycoproteins on surface of WBCs. WBCs normally move through blood vessels but they may need to leave sometimes as part of inflammation response. They do this via change in cell-cell adhesion interaction. WBCs express glycoproteins so u get interaction of selectin and glycoproteins. It is weak interaction but can turn ON/OFF |
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What can reduced cell adhesion result in? |
CANCER Cells can migrate Loss of cell- cells adhesion Loss of cell-ECM adhesion (change in integrin signalling = subtypes are expressed = MUTATIONS All these changes impact SIGNALLING |
