CB20 Cell Adhesion

Question 1

List the various cell-cell & cell-matrix interactions that are required for tissue assembly

Answer 1

Tight junctions
Adheren junctions, desmosomes, hemidesmosomes
Gap junctions

Cell-matrix interactions via integrins

Question 2

Describe the role of tight junctions

Answer 2

Tight junctions bind neighbouring cells together to form an impermeable seal
The seal is made from proteins called Claudius & occludins

• Prevent leakage
• also required for maintaining asymmetry of the distribution of integral
• tight proteins Keep proteins in their location to carry out their function

Question 3

Comment on variations in the ‘tightness’ of tight junctions

Answer 3

Tight junctions vary in tightness in a tissue-dependent manner due to the amount of claudins & occludins

Question 4

Explain the role of cadherins in the cell

Answer 4

Cadherins are responsible for cell binding within the plasma membrane
Cadherius are tethered to the actin cytoskeleton via linker proteins

Question 5

Explain the role of integrins in cell-matrix anchoring junctions

Answer 5

Cells are attached to extracellular matrix by fibronectin & interns
Integral molecules transmit tension across the membrane

Question 6

Account for the consequences of autoimmune attack on desmosome caherins

Answer 6

Desmogleins are targeted (family of cadherens)
Autoantibodies form against desmogleins

When autoantibodies attack desmogleins, the cells become separated from each other

Question 7

Explain the structure & function of gap junction

Answer 7

Gap junctions allow ions & small molecules to pass from cell to cell ( ~ 2nm)

The gap contains protein complexes called connections which form channels across the two membranes creating electrical & metabolic coupling between the cells