Vesicular Transport Flashcards
What are the 3 types of transport vesicles?
- Clathrin coated
- COP I
- COP II
What is the COP II protein coat made of?
Cytosolic components
What are the vital components of vesicle formation?
GTPases
Adaptor proteins
Coat
What are the names for the components of vesicle formation?
GTPase - Sar1
Adaptor protein - Sec23/24
Coat - Sec 13/31
What is the active form of a GTPase?
GTP
What is the inactive form of a GTPase?
GDP
What is a GEF?
Guanine nucleotide exchange factor. (GDP~>GTP)
What is a GAP?
GTPase activating protein. (GTP~>GDP)
How is a COPII vesicle formed?
Signal (cargo adaptor) is recognised by adaptor protein Sec24.
Activates Sec 23 which activates GTPase, converts GDP ~> GTP.
Recruitment of coat proteins (Sec13/31) to membrane.
Bud is pinched off to form vesicle.
What is reconstitution used for?
To see what makes up a COP II vesicle.
What is needed to be added to ER to make COP II vesicles?
Cytosol
ATP
GTP
How do you separate vesicles from ER in vitro?
By centrifugation in a sucrose solution
Vesicles and ER are different densities so will settle in different bands.
How is cytosol harvested from cells?
Break open the cells, remove all membranes and leave all soluble materials.
What did the assay after reconstitution show?
By adding cytosol, ATP and GTP, there was p58 but no ribophorin. So they are free from ER components.
How are GTPases recruited curing COP II formation?
Sar1-GDP is recruited to the membrane by GEFs.
GDP ~> GDP
Sar1-GTP recruits Sec23/24 and Sec13/31
