Retrograde transport from the prevacuolar compartment to the trans-Golgi network

Forward transport through the endomembrane system is balanced by backward or retrograde transport that retrieves and recycles membrane lipids, trafficking machinery and cargo receptors. In this review, we focus on retrograde transport from the prevacuolar compartment/multi-vesicular bodies to the trans-Golgi network. This requires components of the retromer complex, which is hypothesized to form a coat on retrograde transport vesicles, and also SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) complexes and associated proteins, required for vesicle fusion with the trans-Golgi network. We discuss recent research on the mechanism and possible physiological consequences of this trafficking and remaining controversies and unanswered questions regarding the trafficking pathways.