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. 2022 Feb 4;479(3):273–288. doi: 10.1042/BCJ20210719

Figure 1. Schematic overview over the steps involved in the the targeting of a trafficking vesicle.

Figure 1.

The figure shows a typical sequence of molecular steps governing the delivery and fusion of a trafficking vesicle to the correct target compartment. Formation of a trafficking vesicle by budding (not depicted here) frequently involves protein coats. Once these coats are disassembled, the molecular zip codes become “visible” to cytoplasmic proteins and are activated, for instance by GDP-GTP exchange or by phosphorylation/dephosphorylation of PtdIns variants. Active zip codes recruit tethering factors from the cytoplasm which, after transport along cytoskeletal tracks (not shown here), bind to a docking receptor on the target compartment. SNARE proteins are then activated by members of the conserved SM- and CATCHR protein families, followed by SNARE assembly and membrane fusion. After fusion, zip codes are switched off, tethering and activation factors dissociate, and the assembled SNARE complexes are disassembled (not shown). See text for details.