Fig. 9. A schematic model depicting the recycling pathway of VAMP4. VAMP4-EGFP internalized from the surface by clathrin-mediated endocytosis is firstly delivered to the sorting endosomes (SE) labeled with EEA1 and TfR and then transported to the peri-Golgi REs labeled with TfR and revealed by its accumulation there when cells were incubated at 18°C or treated with BFLA1 or conA before being delivered to the TGN. The di-Leu motif of its TGN-targeting signal is necessary for the internalization from the surface whereas the distal acidic cluster is involved in efficient delivery from the endosome to the TGN. The strong correlation of the signal responsible for TGN targeting and recycling indicates that this recycling pathway contributes to the steady-state enrichment of VAMP4 in the TGN. The elucidation of this recycling pathway is in line with the function of VAMP4 as a v-SNARE participating in trafficking from the REs to the TGN.