Cell Junctions Flashcards
why are cell interactions so important?
for recognition, communication and adhesion
what are the types of linked cell interactions?
desmosomes, adhesion and tight junctions
what type of junction is not interactive?
gap junctions
what are desmosomes?
anchoring junctions in epithelia
what is the core of the desmosomes made up of?
glycoproteins
what do the connecting filaments do in desmosomes?
join the core and the plaques
how to the connecting filaments work in desmosomes?
use cadherins and homophilic binding
what do the tonofilaments do in desmosomes?
connect the plaque to the cytoskeleton and the organelles
what do hemidesmosomes do?
join cells to the basal lamina
what is the basal lamina?
layer of ECM secreted by epithelial cells
where are desmosomes useful?
tissues such as cardiac and intestine as they form an adhering band
how are adherons junctions similar to desmosomes?
use transmembrane proteins such as cadherins
where do the transmembrane proteins attach in adherons junctions?
tethered with linker proteins to actin filaments
why are adherons useful?
form contractile networks in epithelial tissue
where are adherons important?
useful in development such as formation of the neural tube and lens vesicle
what are tight junctions?
zipper like connections for very close intercellular contact
what is the function of tight junctions?
prevent passage of materials between cells so that they must pass through the membrane
why are tight junctions useful?
allows membrane asymmetry and for cells to control passage of materials
what do gap junctions do?
provide gaps between cells that prevent ionic coupling, cooperation and synchronisation
what is the structure of gap junctions?
hexagonal proteins with a central pore called connexons
what molecules pass through gap junctions?
cyclic AMP, nucleotides, glucose
what things to cell-cell adhesion depend on?
calcium, magnesium and temperature
how are tissues abe to reaggregate into a tissue hierarchy?
differential adhesion hypothesis
what are the features of CAM’s?
some have broad tissue distribution yet some are tissue and time specific, some need calcium ions
