Cell Junctions Flashcards
what makes integrin iniquie from other cell adhesion molecules/receptors?
integrin does not bind to another cell; instead, binds to fibronectin
B-catenin role with cadherins
cytosolic domains of cadherin bind directly or indirectly to adapter proteins (such as beta-catenin) that connects the junctions to actin filaments of cytoskeleton and participate in intracellular signaling pathways
where are gap junctions ususally found?
myocardial cells and uterus
important role of selectins
play a role in neutrophil rolling; when white blood cells roll toward site of inflammation they interact with selectin near the site – how they know to stop at the site
cadherin function and requirements for function
- involved in adhering cells together
- requires
- both Cis- and Trans-binding
- calcium for binding
hemidesmasome
cell to extracellular matrix junction; intermediate filament attachment site
composition of cytoplasmic plaque
aggregate of individual proteins that end up looking like a disc
gap junctions / communication junctions structure
6 connexin proteins (transmembrane proteins) associate to make connexon; 2 connexons sit across from one anotherto make a channel-like pore
major families of cell-adhesion molecules and adhesion receptors
- cadherins
- Ig-superfamily
- integrins
- selectins
specificity of gap junctions
anything smaller than 1200 daltons can pass through; not specific, just depends on size
cel-adhesion molecules/receptors with homophilic interaction
cadherins and Ig-superfamily
cell-adhesion molecules with heterophilic interactions
integrins and selectins
separating cells
use trypsin and EDTA
trypsin – degrades cadherin
EDTA - complexes away calcium
common species for studying cell junctions
sponges
integrin receptor function
allows the cell to sense its surroundings/environment
can sense mechanical change (example: stretching exposes bindings site on the integrin)
interaction of cells with same adhesion molecules
cells with the same adhesion molecules find each otehr and aggregate together
anchoring junctions
purpose: holds cells together
cadherins interact with one another for binding and are anchored to a cytoplasmic plaque; the cytoplasmic plaque then interacts with intermediate filaments
gap junctions response to increased calcium levels
gap junctions close when there are increased levels of calcium because high cytoplasmic calcium concentration can be a sign of damage; closing prevents other cells from getting damaged
desmasome
cell to cell junciton; intermediate filament attachment sites
tight junctions purpose
to seal cells together and prevent flow of substance between cells (like flow of water between cells)
CAM acronym
cell adhesion molecule
