1What kind of destinations do COP1 and COP2 coated vesicles handle?
COP2 vesicles are in charge of transporting vesicles from ER to Golgi.
COP1 vesicles are in charge of transporting escaped resident proteins from Golgi back to ER.
2Where do vesicles bud off from the ER membrane?
Exit site regions
3Why do some cargo proteins (both membrane and soluble) leave the ER while others do not?
Because the cargo proteins have an exit signal recognized by COP2 components.
4What is homotypic fusion?
After transport vesicles have bud off ER and shed their coats they will begin to interact with other vesicles.
With the help of matching SNARES the vesicles will fuse with each other.
5What are vesicular tubular clusters?
Structures that form from homotypic fusions.
Function as transport packages that bring material from ER to Golgi.
Bud's vesicles off coated with COP1.
6What role do Vesicular Tubular Clusters play in the "Retrieval Pathways"?
The VTC will be in charged of shipping escaped resident proteins back to the ER. Proteins with the KDEL retreival signal will be returned.
7What do ER resident proteins membrane/soluble contain that makes the ER their target or permanent destination?
A KDEL sequence/Retrieval signal at their c terminal end.
Binds to KDEL receptors
8Explain how KDEL receptors function:
KDEL receptor will bind to any multipass transmembrane protein with KDEL sequence
Gets packaged into a COP1 coated transport vesicle.
9How does KDEL receptor affinity differ in ER and Golgi?
KDEL sequence affinity is higher for receptors in tubular clusters of golgi due to escaped resident proteins.
KDEL sequence affinity is lower for receptors in ER due to unloading of cargo.
10What are the 2 faces Golgi? What are they both referred as?
Cis face (vesicle entrance) and trans face (vesicle exit). The CGN or cis golgi network and the TGN or trans golgi network.
11_____ and _____ enter the CGN and exit the TGN. What are the 2 fates of proteins entering the CGN and exiting the TGN?
Proteins, Lipids.
They can either continue in Golgi or returned to ER.
Exiting they are sorted to next destination: lysosomes, vesicles, cell surface.
12Explain maturation model of golgi cisternae:
The vesicles from the ER will begin forming the new CGN of Golgi. The old TGNs proteins will bud off and join the new TGN (old medial cisterna).
13What are proteins glycosated in the ER called? glycosated in the golgi?
Glycoproteins, Proteoglycans.
14Explain O-linked glycosylation:
Synthesized similar to N-linked, Glycosyl transferase in lumen of Golgi.