Trafficking between ER and Golgi Flashcards
How can the secretory pathway be visualised?
using cryo-electron tomography
Why are membrane coat proteins important?
They are involved in cargo selection and curvature generation
Which direction does COPI operate in?
from the Golgi to the ER
Which direction does COPII operate in?
ER to the Golgi
What does sec12 do?
It is the Sar1 GEF and activates Sar1
What happens when sec12 catalyses nucleotide exchange on sar1?
- Recruits Sar1 to ER membrane
- Initiates membrane deformation due to insertion of ampipathic helix into membrane
How can insertion of an ampipathic helix cause membrane deformation?
Can push into outer leaflet of lipid bilayer and promote curvature of membrane
What does Sar1 recruit?
The heterodimeric complex sec23/24
- Where doe sec23 component bind?
- Where does sec24 component bind?
- Sec23 binds to sar1
- Sec24 binds to membrane cargo proteins
What captures soluble cargo?
Transport adaptors in the lumen of the ER
What binds and collects the pre-budding complexes at ER exit sites?
Sec13-31 heterotetramer
What leads to fission of a vesicle from the donor ER membrane?
Progressive assembly of fully coated COPII vesicle
What triggers COPII coat dissasembly?
Hydrolysis of GTP bound to SAr1
Where does COPII recognise sorting motifs?
In cytosolic domains of membrane proteins
What forms the cotamer complex of COPI coat?
Adaptor and cage
