Figure 2.

Cargo sorting at the TGN: (A) schematic showing the process of membrane recruitment of the adaptor protein complex, AP-1, and the binding of sorting motifs on the cytoplasmic tail of cargoes. GTP-bound membrane-associated small G protein Arf1 recruits cytosolic AP-1 to the TGN membranes. Arf1 also induces conformational change in AP-1, from closed to an open conformation, to allow the binding of cargo sorting motif(s). The μ1 subunit (green) binds tyrosine-based sorting motif (YXXΦ, green cargo) and the σ1−γ subunits bind dileucine sorting motif (DE)XXXL(LI), brown cargo). (B) Schematic representation of the membrane recruitment of AP complexes by active small G proteins, followed by binding of AP complex to the cytoplasmic tail of cargo proteins. Subsequently, the hinge-ear extensions of each AP complex mediate the recruitment of coat and accessory proteins to drive membrane curvature and vesicle formation.