What is the main function of ARF-GTP in vesicle formation?
Budding of AP1, AP3 and GGA clathrin-coated vesicles at trans-Golgi network and endosomes requires activated ARF1 small GTPase cycling between GDP and GTP states. ARF1-GDP cytosolic bound to GDI-like factor; activation by large ARF GEFs BIG1-BIG2 at TGN and GBF1 at Golgi exchange GDP for GTP upon membrane recruitment mediated by HDS domains sensing curvature and lipid composition. ARF-GTP undergoes structural rearrangement exposing N-terminal myristoylated amphipathic helix inserting into outer leaflet and effector binding interface. Effectors include heterotetrameric AP1 via gamma subunit tru
Ref: Lodish et al., MCB Chapter 14: ARF1-GTP recruits AP1/GGA to initiate clathrin coat at TGN.