Intracellular Protein Trafficking (2) Flashcards
Define glycosylation
Addition of sugar to protein/lipid
Which translocon is involved in cotranslational tranlocation into the ER?
Sec61 complex
What is the role of chaperones in the ER lumen?
Fold protein
Where does N-linked glycosylation occur and describe the process
ER
On asparagine of N-X-S/N-X-T sequence
Using oligosaccharyl transferase -n binds to Sec61, asparagine, and ribosome
How does glycosylation affect a protein?
Causes folding - increases stability - involved in cell adhesion
What marks incorrectly-folded proteins for degradation?
Chaperones
What are the signals for directing proteins from the ER to the correct organelles?
AA sequences
Protein modifications - glycosylation, ubiquitination, lipid modifications
How do vesicles contain the correct soluble cargo protein?
Cargo-receptor proteins face into vesicle
Name the main cargo-receptor proteins
COPI, COPII, clathrin (and adaptor proteins)
Which transport step is COPII involved in?
ER to cis-Golgi
What does COPII consist of?
Sec proteins
Which GTPase is associated with COPII and what is its role?
SarI-GTPase
For assembly and disassembly of coat
What are the overall characteristics of COPII coats?
Selective and structural
Which transport step is COPI involved in?
Cis-Golgi to ER
Later to earlier Golgi cisternae
What does COPI consist of?
Coatomers
