Lecture 17- Degradation Of Misfolded Proteins

Question 1

Where are misfolded protein degraded?

Answer 1

So misfolded protein are retained in ER for first being correctly folded but if it doesn’t fold correctly it has to be destroyed.
For destruction the protein are transported to the cytosol and to the proteosomes for degradation

Question 2

Why is it necessary for misfolded proteins to be destroyed

Answer 2

The degradation of proteins in proteasome is called - ER association degradation
This ensures that the misfolded proteins don’t reach the cell surface and secrete out of the cell

Question 3

What keeps the 3 sensors,that activate UPR, inactive?

Answer 3

BiP- inhibitory chaperones , but if misfolded proteins accumulate in the ER they are not able to keep the sensors inactive

Question 4

What do the activated sensors stimulate?

Answer 4

They stimulate

• the production of tfs that activates genes encoding chaperones or other proteins involved in ER quality control
• inhibit protein synthesis , reducing the flow of proteins through the ER

By these each sensor stimulates a component of UPR