adhesion molecules (questions in lecture) Flashcards
What are the adhesion molecules that form occluding/tights
junctions?
clauddins and occludins
Where are the occluding/tight located?
apical region
What do the adhesion molecules recognize on a neighbouring
cell, i.e. what is their ‘ligand’?
Claudins and occulins recognise the same molecules on neighbouring cells
claudins bind claudins on adjacent cells
What are molecules associated with the cytoplasmic side of
the adhesion molecules?
ZO proteins link claudins and occulins to actin filaments of cytoskeleton
Which cytoskeletal element are tight junctions connected to?
actin filaments
What is the main function of tight/occluding junctions ?
form a protective barrier/ diffusion barrier
What are the two main anchoring junctions that mediate
adhesion BETWEEN cells?
adheren junctions and desmosomes
What are the adhesion molecules that form anchoring junctions?
cadherins and desmosomal cadherins
name the desmosomal cadherins
desmoglein
desmocollin
What do the adhesion molecules of anchoring junctions recognize on a
neighbouring cell, i.e. what is their ‘ligand’?
adheren junctions recognise catenins (a-catenin, b-catenin p-120)
desmosomes recognise desmoplankin, plankofilin and plankoglobin
Which cytoskeletal element are each of these anchoring
junctions connected to?
cadherins bind to actin filaments
desmosomes bind to intermediate filaments (e.g keratin)
What is the main function of anchoring junctions ?
Adherens Junctions: Mediate dynamic cell-cell adhesion
desmosomes provide mechanical strength
name the integrins
focal adhesions
hemidesmosomes
What are the adhesion molecules that form focal
adhesions?
integrins
where are focal adhesions located
basal membrane connect cell to ECM
What do the adhesion molecules of focal adhesions recognize i.e. what is their
‘ligand’?
extracellular maxtrix proteins:
Fibronectin
Collagen
Laminin
Vitronectin
how many subunits are there in focal adhesions
2
a-intergin and b-integrin
What are other molecules associated with the cytoplasmic
side of the adhesion molecules (focal adhesions)?
vinculin
talin
focal adhesion kinase
Which cytoskeletal element are focal adhesions connected
to?
actin filament
what is the main function of focal adhesions
cell-ECM adhesion
cell migration
signal transduction
force transduction
What are the adhesion molecules that form hemidesmosomes?
a6B4 integrins
where are hemidesmosomes located
basal membrane
What do the adhesion molecules of hemidesmosomes recognize i.e. what is their
‘ligand’?
lamins link a6B4 integrins to collagen
What are other molecules associated with the cytoplasmic
side of the adhesion molecules (hemidesmosomes)
plectin
Which cytoskeletal element are hemidesmosomes connected
to?
intermediate filaments (keratin)
main functions of hemidesmosomes
cell-ECM adhesion
cell signalling
What is a directly communicating junction?
gap junction
What are the adhesion molecules that form gap junctions
connexons (6 connexins)
Zonula occludens (ZO) proteins role in gap junctions
These scaffolding proteins help organize connexins within the plasma membrane and can mediate their connection to the cytoskeleton
how can calmodulin modulate gap junctions
in response to changes in calcium levels, which can open or close the connexons.
