Vesicular Traffic, Secretion And Endocytosis Flashcards
What governs all protein trafficking in the secretory pathway?
Transport of membrane and soluble proteins is mediated by transport vesicles that collect cargo proteins in buds and deliver them by fusing with the membrane of another compartment.
What drives the budding of vesicles from their parent membrane?
The polymerization of soluble protein complexes onto the membrane to form a proteinaceous vesicle coat.
What are the three types of coated vesicles?
COPII vesicles
COPI vesicles
Clathrin vesicles
What is the main function of COPII vesicles?
COPII vesicles transport proteins from the rough ER to the Golgi.
What is the primary transport direction of COPI vesicles?
Mainly transport proteins in the retrograde direction between Golgi cisternae and from the cis-Golgi back to the rough ER.
What do clathrin vesicles transport?
Clathrin vesicles transport proteins from the plasma membrane and the trans-Golgi network to late endosomes.
What type of GTP-binding protein is associated with COPI and clathrin vesicles?
ARF
What GTP-binding protein is found in COPII vesicles?
Sar1.
What is the role of ARF and Sar1 in vesicle coats?
They are monomeric proteins that control coat assembly and cycle between inactive GDP-bound and active GTP-bound forms.
What signal is recognized by the KDEL receptor?
The KDEL sorting signal.
Where is the KDEL receptor primarily found?
On small transport vesicles shuttling between the ER and the cis-Golgi and on the cis-Golgi reticulum.
Fill in the blank: COPII vesicles transport proteins from the rough ER to the Golgi; _______ vesicles mainly transport proteins in the retrograde direction between Golgi cisternae and from the cis-Golgi back to the rough ER.
COPI
Fill in the blank: _______ vesicles transport proteins from the plasma membrane and the trans-Golgi network to late endosomes.
Clathrin
True or False: All vesicles have the same type of coat proteins.
False.
What is one function of Sar1 in vesicle formation?
Controls assembly and disassembly of COPII coats.
What is the endocytic pathway for internalizing low-density lipoprotein (LDL)?
the pathway is: LDL binding to LDL receptor in clathrin-coated pits → invagination and coated vesicle formation → uncoating to form early endosome → maturation to late endosome (receptor recycling) → fusion with lysosome → hydrolysis of LDL components.
