12 - Princples of Vesicular Transport Flashcards
How is transport mediated?
Through vesicles
How do materials move in and out of the cells?
They move throught the cell in an anterograde action (forward) and out of the cell in a retrograde action.
How do vesicles move from the ER to the Golgi?
They bud off the ER and move to the gogi where it fuses to the membrane.
What are 3 essential components for vesicle formation?
- GTPase
- Adaptor protein (to recognise the cargo)
- Coat protein
What are small GTPases?
Molecular switches.
What is the founding member of the GTPase family?
Ras
When are the small GTPases active?
When they are bound to GTP.
When are small GTPases inactive?
When they are bound to GDP.
How is the GDP converted to GTP?
By guanine exchange factors (GEFs)
How are the molecules inactivated from GTP to GDP?
By the action of GTPase activating proteins. (GAPs)
What are COPII coated vesicles?
Vesicles that form at the exit sites of the ER.
What are the components of COPII coated vesicles?
- GTPase - Sar1 (Arf family)
- Adaptor - Sec23/24
- Coat - Sec13/31
How are COPII vesicles formed?
- Cargo is recognised by the adaptor
- Sar1 GTPase is activated.
- Sec23/24 adaptor complex allows the outer protein coat to be recruited.
- The bud is formed and then pinches off to form vesicles.
What helps us understand what makes a COPII vesicle?
Reconstitution experiments.
