Biogenesis of membrane proteins

Question 1

What are the names of the translocator in bacteria vs in euks?

Answer 1

bact: SecY
subunits are Y, E and G
euks: Sec61
subunits are α, β and γ

Question 2

What are the 3 types of signals which initiate topogenesis in membrane proteins?

topogenesis = formation of tertiary structure

Answer 2

-cleavable signals (for single-pass membrane proteins)
-signal-anchors (internalised, not cleaved; N’ t on inside)
-reverse signal-anchor (internalised, not cleaved; N’ t on outside)

Question 2

What are the names of the receptor involved in translocation in bacteria vs in euks?

Answer 2

bact: Fts
euks: SRP receptor

Question 3

What factors affect the orientation of membrane proteins?

Answer 3

-charge differences (positive inside rule)
-folding of N-terminal domain (large N-t more likely to stay inside rather than pass through translocator)
-hydrophobicity