Week 5 Bollough Lecture 2

Question 1

What are the uses of lipid anchors?

Answer 1

Hydrophobic lipid anchors enable some proteins to associate with the lipid bilayer

Question 2

What are the types of lipid anchors?

Answer 2

3 types

a) Acylation
b) Prenylation
c) GPI anchor

Question 3

What is acylation?

Answer 3

Acylation is the process of adding an acyl group to a compound

Question 4

What is an acyl group?

Answer 4

C=O bonds

Question 5

Explain acylated lipid anchors?

Answer 5

Amide bond to N-terminal glycine residue; The sequence is joined by a glycine molecule at the N-terminal end, forming an amide bond (inner leaflet)

a) Happens co-translationally; N-terminal methionine is removed
i) Can occur by myristoulation
ii) Palmitoylation

Question 6

Explain prenylation lipid anchors?

Answer 6

Thioether bond to C-terminal cystine (inner leaflet)

a) Happens to Farnesyl (15c) or geranygeranyl (20c)
i) Posttranslational modification C-terminal sequence, need 2 aliphatic amino acids
ii) The 2 aliphatic amino acids, plus another one after them, is cleave after attachment

Question 7

What is an aliphatic amino acid?

Answer 7

Amino acid that is non-polar and hydrophobic

Question 8

Explain GPI lipid anchors?

Answer 8

Modify C-terminus with ethanolamine (exterior leaflet)

Question 9

why are methods of lipid anchoring not suitable for membrane proteins that need to transfer substances or signals across membranes?

Answer 9

The anchors don’t go through the membrane, only in one leaflet.