Exocytosis and Endocytosis: Transporting Material Across the Plasma Membrane

Question 1

Recycling plasma membrane receptors: what happens to receptors from the plasma membrane? Due to?

Answer 1

receptors from the plasma membrane are recycled due to acidification of the early endosome

Question 2

Recycling plasma membrane receptors: what happens to the pH as the endosome matures?

Answer 2

The pH gradually lowers as the endosome matures, facilitated by an ATP dependent proton pump

Question 3

Recycling plasma membrane receptors: What does the lowered pH do?

Answer 3

dissociates ligand and receptors, allowing receptors to be returned to the membrane

Question 4

Alternate fates for ligand-receptor complexes: (3)

Answer 4

1. some complexes are carried to a lysosome for degradation
2. some complexes are carried to the TGN, where they enter a variety of pathways
3. complexes can also travel by transport vesicles to a different region of the plasma membrane, where they are secreted (transcytosis)