Chloroplast transport

Question 1

What are the signal peptides needed for
ER targetting
mitochondrial targetting
Stromal targetting
Thylakoid targeting- Sec pathway and TAT pathway

Answer 1

ER- hydropbobic domain
mitochondial-Amphpathic helix
Stromal Targetting- high in hydroxlated AA and serine and theorine(phospho) residues
Sec sytem- +ve residues, hydrophobic domain with enzyme cleavage site
TAT pathay-Twin arginine motif eseential (TAt), can have phe,lys,arg in specific positions(bacteria), some plants have c terminal basic residues

Question 2

What are the 4 pathways to targetting the thylakoid

Answer 2

TAT
Sec
SRP-Alb- Insertion
Spontaneous-Insertion

Question 3

What are the components of stromal transport

Answer 3

Toc159(SRP like) GTPase domain
Toc34(SRPR like)
Import pore(reversible contacts with peptide) Toc75
chaperones( TIC22 recuits Hsc70) 
To TIC import pore(TIC110 and 20)
Pullng force(TIC110 recruits chaperones)

Question 4

TAT pathway components in translocation of folded substates

Answer 4

TAT operon ABCDE
TATBC initial contact with signal helix
TATA- recuits and oligomerises to form pore(PMF dependant)

Question 5

SRP-Alb membrane insertion pathway components

Answer 5

post tranlational SRP54/SRP43 then Alb

co translational- SRP43 and SecY/E(nascent chain recognition