Transport-vesicle targeting: tethers before SNAREs.

Protein secretion and the transport of proteins between membrane-bound compartments are mediated by small, membrane-bound vesicles. Here I review what is known about the process by which vesicles are targeted to the correct destination. A growing family of proteins, whose precise modes of action are far from established, is involved in targeting. Despite the wide diversity in the identities of the players, some common themes are emerging that may explain how vesicles can identify their targets and release their cargo at the correct time and place in eukaryotic cells.