Protein Trafficking Between Flashcards
The coat is key for efficient tethering and docking to the target membrane. True or false. Why?
False. The tethering and docking cannot take place if the coat is in the way
What are the members responsible for exocytosis?
The ER buds a COP2 vesicle, which only goes in the forward direction. The coated vesicle goes from
Cis Golgi to Trans Golgi and is transported to the plasma membrane.
What are the members responsible for endocytosis?
-Early endosome
-Late endosome
-Lysosome
-Essentially, the plasma membrane buds a clathrin coated vesicle to be delivered to an early endosome to a late endosome (cis to trans) then to a lysosome.
What is the fate of a vesicle in endocytosis?
It fuses with a lysosome
What is the proper sequence of compartments visited by proteins destined to be secreted from eukaryotic cells? (AKA exocytosis)
ER->Cis Golgi->Trans Golgi-> Plasma membrane via “post Golgi vesicle”
Neurofilament proteins (NF-L, NF-M, NF-H) are found primarily near the MTOC in neuronal cells, where they stabilize the organization of the endoplasmic reticulum and Golgi complex. True or false
True
Where are neurofilament proteins primarily found?
Near the MTOC in neuronal cells
What do neuronal filament proteins do?
They stabilize the organization of the endoplasmic reticulum and Golgi complex
COP II vesicles are the only ones that travel from the ER to the Golgi
True, they provide the only route of vesicular exit of the ER (only move in forward direction)
What is the regulatory mechanism of exocytosis?
Temporary storage in secretory granules until the cell is stimulated for exocytosis to occur.
Retrograde transport refers to movement of vesicles from ___ to ___.
Golgi to ER
How are vesicle exiting the endoplasmic reticulum formed?
COP II proteins select cargo and initiate budding from the ER and a scission protein cleaves the vesicle and reforms the ER.
How are vesicle exiting the endoplasmic reticulum formed?
COP II proteins select cargo and initiate budding from the ER and a scission protein cleaves the vesicle and reforms the ER.
What is the targeting signal used to retain resident Golgi proteins? (There are two)
Membrane spanning domain and flanking sequences
SNAREs are not used for tethering. True or false. Why
False. They are vital for tethering and docking
COP I vesicles not only provide transport from the Cis Golgi Network to the trans Golgi network, but also retrieve proteins with a KDEL sequence from VTCs or Golgi and return them to the ER. True or false. Why?
True, this is because they can retrograde and go forward.
The role of coat proteins in vesicle trafficking is to __.
Select the appropriate cargo to define the vesicle type, and they make it easier for the transport vesicle to form via direct and indirect binding.
Prior to fusion of a transport vesicle to its target membrane, what step has to happen?
Tethering and docking have to occur. Also, the vesicle needs to be released of its coat proteins so that it can begin to tether.
What controlls the tethering?
The RAB protein sequence
What controls the docking?
V-SNAREs interacting with T-SNAREs.
Retrograde transport from the Golgi complex to the ER occurs through ___ vesicles
COP I
What would a cell lacking functional T-SNAREs look like?
The transport vesicles would accumulate in the cytoplasm due to the inability to bind to the target membrane.
NSF unwinds the V-SNARE/T-SNARE complex to allow fusion during docking. True or false. Why?
False. While NSF does unwind the two complexes, it does this AFTER fusion has already occurred. The winding is necessary for the docking to occur in the first place.
What are the facilitating roles of SNARE proteins?
The function of SNARE proteins allows for docking to occurs they do this by winding together and bringing the two membranes closer together so they can fuse.
