post-translational modifications

Question 1

list three ways a protein could be modified post-translationally (there are 9)

Answer 1

1. methylation
2. ubiquidation
3. phosphorylation
4. acetylation
5. SUMOylation
6. lipidation
7. hydroxylation
8. glycosylation
9. disulfide bond

Question 2

list 2 reasons why glycosylation could be important for a protein’s function

Answer 2

• carbohydrates are hydrophilic so they change the polarity and solubility
• serve as markers for protein to get to its cellular destination
• structural complexity forms a code
• facilitate cell-cell interactions

Question 3

what is one reason why lipidation could be important for a protein’s function?

Answer 3

• allows proteins to anchor in the membrane
• involved in cellular signal transduction
• helps in protein-protein interaction

Question 4

what is the most common function of ubiquidation?

Answer 4

• labeling proteins for proteasomal degradation

Question 5

what is a signal sequence?

Answer 5

• direct proteins to their cellular destination

Question 6

what is an example of a type of signal sequence that would not be cleaved?

Answer 6

Nuclear localization sequences (NLS) are not cleaved

Question 7

preprotein

Answer 7

• protein precursor that contains a signal peptide sequence that is cleaved