Changing directions: clathrin-mediated transport between the Golgi and endosomes.
Clathrin-coated vesicles mediate transport between the trans-Golgi network (TGN) and endosomes. In recent years there has been tremendous progress in identifying factors involved in anterograde and retrograde transport steps. The well-characterised heterotetrameric clathrin adaptor complex AP-1 has long been thought to mediate anterograde transport from the TGN to endosomes. However, recent studies of AP-1-knockout mice implicate AP-1 in retrograde as well as anterograde transport. The recently identified Golgi-associated, gamma-ear-containing, ARF-binding (GGA) proteins share functional similarities with tetrameric adaptor complexes and are essential for anterograde transport of mannose-6-phosphate receptors, the sorting receptors for soluble lysosomal enzymes. To date, it is not clear whether GGAs and AP-1 mediate transport in different directions, act in parallel pathways, or cooperate in the same transport steps. Recent data have shed light on the locations, functions and interactions of AP-1 and GGA proteins. These data provide support for the role of both in anterograde transport from the Golgi complex.
Hinners
Ina
I
Secretory Pathways Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
Tooze
Sharon A
SA
D020727:ADP-Ribosylation Factors / Q000502:physiology; D033961:Adaptor Protein Complex 1 / Q000502:physiology; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D002352:Carrier Proteins / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002966:Clathrin / Q000502:physiology*; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D010766:Phosphorylation; D021381:Protein Transport; D021601:trans-Golgi Network / Q000378:metabolism*
D033961:Adaptor Protein Complex 1; D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D002966:Clathrin; C407306:GGA adaptor proteins; D008565:Membrane Proteins; D020727:ADP-Ribosylation Factors