adhesion molecules Flashcards
4 types of cell-cell junctions in epithelia
adherens junctions
desmosomes
tight junctions
gap junctions
3 functional categories of cell cell junctions
anchoring junctions
tight junctions
gap junctions
protein that mediates adherens junctions
classical cadherins
what are adherens junctions connected to
actin cytoskeleton
what are the classical cadherins
ENP cadherins
what do cadherins do
calcium binds to cadherins and stabilises the flexible linkers
this facilitates binding of cadherins between cells
experimental evidence of cadherins in cell adhesion
E cadherin introduced to L cells and E cadherin was found to preferentially adhere to other E cadherin cells via calcium dependent aggregation
adaptor protein in adherens junctions
alpha and beta catenin
how do desmosomes differ from adherens junctions
they use desmosomal cadherins (desmoglein, desmocollins) rather than classical ones
what are desmosomes connected to
intermediate filaments
what adaptor proteins are associated with desmosomes
desmoplakin
another name for tight junctions
zona occludens
function of tight junctions
form a seal between cells preventing movement of water and solutes between cells
prevents movement of membrane lipids between apical and basolateral surface
protein components of tight junctions
occludins and claudins
adaptor protein in tight junctions
ZO-1
structure of occuludins and claudins
have transmembrane domains forming loops that form non covalent interactions with loops from adjacent cell
what are gap junctions made of
connexin proteins, one from each cell and they join in the middle
structure of connexon
6 connexion proteins in a wheel shape
why are gap junctions diverse
they can be homomeric or heteromeric depending of the connexin used
also homotypic/ heterotypic
function of gap junctions
allow small molecule transport
intergrate metabolic processes by passing secondary messengers to adjacent cells
facilitate rapid transmission of electric signals in neurons
structure of plasmodesmata
gap junction in plants, plasma membranes merge to for annulus channel, extension of ER called desmotubule
