Unit 6.2: Protein Sorting to Organelles

Question 1

Two main mechanisms that control exit of proteins from the ER

Answer 1

1. Quality control
2. Active cargo selection

Question 2

Quality control of proteins that exit ER

Answer 2

If the protein is not folded and the protein complex is not assembled, it is actively retained by ER-localized chaperones

Question 3

Active cargo selection of proteins that exit from the ER

Answer 3

Specific cargo collected in regions of the ER that will pinch off to form a transport vesicle.

Soluble cargo are recognized by membrane proteins that span the ER bilayer.

The membrane cargo can be recognized by cytosolic proteins that will aid in vesicle formation.

Question 4

Some proteins that are resident ER proteins may mistakenly

Answer 4

Exit the ER