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38 Cards in this Set
- Front
- Back
Folding of the neural tube occurs because of contraction of bundles of _______ ____ __________ |
apical actin filaments |
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Types of cell junctions |
anchoring tight gap |
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Types of anchoring junctions
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Adherens Junctions (between cells) Desmosomes (between cells) Hemidesmosomes (on basal surface aka cell-matrix) |
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AdherensJunctions |
Connectthe lateral membranes of adjacent epithelial cells. Found near the apical surface below tight junctions. It is acircumferential belt of actin and myosin filaments Acts as a tensioncable that can brace the cell and control its shape. |
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cell adhesion molecules (CAMs) |
Cells adhere to each other and the extracellular matrixthrough these |
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Inadherens junctions, the main CAM is... |
Cadherin |
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“Classical”cadherins include (3) |
E-cadherin (epithelial tissue) N-cadherin (neural tissue) P- cadherin (placenta tissue) |
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two major classes of CAMs |
Homophilic and Heterophilic |
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CAMs associatewith different adaptors, which can either link upto the.... |
microfilaments or intermediate filaments. |
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CAMs recruit ___ ________ ______ and control ____ ___________. |
cell signaling proteins gene expression |
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Main classes of extracellular matrix proteins (ECMs) |
proteoglycans collagens multiadhesive matrix proteins |
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Cadherin adhesion is ____ dependent. |
Ca++ |
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Cell-cell adhesions involve two types ofinteractions: |
cis (intracellular or lateral interaction) trans (intercellular interactions) |
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A classical cadherin |
1 transmembrane domain N-term extracellular space domain C-term cytosolic domain 5 extracellular domains |
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Cadherins are regulated by |
Catenins |
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Cadherins && cancer |
α-catenin is suppressed in some types of tumors. When this occurs cells can break free from the tissue and invade the restof the body (metastasis). |
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Regulationof ________ occurs during neural crest cell migration. |
p120-catenin |
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Desmosomes |
cell-cell junction Help transmit shear forces Providestrength and rigidity Makeattachments to intermediate filamentsand use desmosomal cadherins as theirCAMs. |
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2 specialized desmosome cadherins |
desmoglein and desmocollin |
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Hemidesmosomes |
cell-matrix junction On the basal surface of epithelial cells. Attach the cell to the basal lamina using the integrin (α6β4). Interact with intermediate filaments. Mainly found in epithelial cells |
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IgCAMs (NCAMs) |
mediate cell-cell adhesions in neurons immunoglobulin domains in extracellular region homophilic interactions Not sensitive to Ca++ |
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Tight Junctions |
Seal off body cavities like intestinal lumen and brain to set up body compartments prevent diffusion of macromolecules and most other molecules help maintain cell polarity |
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tight junctions are destroyed by |
the protease Trypsin |
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Tight junction composition |
Composed of thin bands of plasma membrane Principal CAMs are occludin and claudin the proteins have 4 TM domains/helices |
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The C-terminal domain of occludin |
binds adapter proteins, which then bind the actin cytoskeleton and signaling proteins. |
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Integrins |
CAM used in hemidesmosomes functions in cell motility, formation, and the regulation of cell life, replication, and death |
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What is the basic structure ofintegrins? |
heterodimers α and β subunits contribute to ligand specificity and requiredivalent cations. |
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Are integrins “receptors” or “ligands”? |
Adhesion receptors for ligands |
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What ECM proteins do integrins bind? |
fibronectin and laminin |
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What are the two conformations ofintegrins? |
low affinity state (bent; cytoplasmic C-term tails are bound) and high affinity states (straight; C-term tails are spread) |
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How is integrin confirmationcontrolled? |
cell signaling |
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When cells are detached from the ECM or attached to thewrong ECM, they initiate _______. |
Programmed Cell Death (apoptosis) |
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What is extravasation? Steps of extravasation |
leukocyte response to infection/inflammation 1. Rolling 2. Activation 3. Adhesion 4. Trans-endothelial migration |
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How is rolling initiated? |
Inflammatory signals deliver P-selectin to the surface ofendothelial cells. Interactions w/ the P-selectin ligand on the leukocytecause them to roll. |
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Leukocyte activation |
Platelet-activating factor (PAF) is a phospholipid that isalso released from the endothelium. It switches the integrins from their low-affinity to highaffinity forms through a G-protein coupled receptor |
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What signal activates integrins? |
PAF (Platelet-activating factor) |
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Leukocyte Adhesion |
Integrins bind ICAM and stop rolling. |
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Leukocyte Extravasation |
leukocytes migrate through the endothelial cells |