Cell adhesion + Migration

Question 1

Steps in migration

Answer 1

1) Protrusion in front of cell in direction
2) Adhesion
3) Traction to pull itself
4) Retraction of cell rear

Question 2

Protrusion

Answer 2

• Uses actin cytoskeleton
• When cell is dormant, actin filament is located near cell surface
• During migration, actin filaments reorganise themselves
• Actin branching + polymerisation take place in one direction, causing protrusion of a broad area of the plasma membrane in front of the cell (Leading edge)

Question 3

Adhesion

Answer 3

• Cells have large sugar proteins called proteoglycans + specialised molecules ie fibronectin that help cells attach to the ECM
• Integrins act as the matrix receptors + help the cells adhere to the ECM and require activation to be used
• Molecules attach to the intracellular domain of integrins to actin filaments

Question 4

Adhesion complexes

Answer 4

• A variety of adaptor/anchor proteins are required to connect integrins to actin filaments in order to provide strength to attach to the ECM
• Similar to actin filament treadmilling, the complexes constantly assemble + disassemble

Question 5

Traction/Tension + Retraction of cell rear

Answer 5

• Requires the use of motor proteins + myosin transports along the actin microfilaments
• In the presence of ATP, myosin will “walk” down the actin filament in the direction of the adhesion complex, pulling the rest of the cell in that direction