Post- Translational Level Flashcards
1
Q
Purpose
A
Newly translated polypeptide chain to coil and fold in a precise manner to assume the unique 3D confirmation of a protein in RER lumen or cytosol
=> functional protein
2
Q
What are the two ways?
A
- Chemical modifications
2. Protein degradation
3
Q
What are the two ways of biochemical modifications?
A
- Glycosylation
2. Phosphorylation
4
Q
Why is biochemical modification necessary?
A
Cleavage and covalent modifications
-> functional proteins
5
Q
Describe glycosylation
A
- covalent addition of short carbohydrate chains to proteins as they pass through RER and GA
- > structural components of the cell surface (glycoproteins)
6
Q
Describe phosphorylation
A
- regulatory proteins are activated/inactivated by reversible addition of phosphate groups
- kinase catalysts the addition of a phosphate group to a protein
- phosphates catalysts the removal of a phosphate group
7
Q
Describe protein degradation
A
- to mark a protein for destruction, cell attacks molecules of a small protein, ubiquitin
- proteasome recognises the ubiquitin-tagged protein and degrades it
