Conserved Molecular Mechanisms Underlying Homeostasis of the Golgi Complex

Figure 2

A model for maintaining Golgi structure during cisternal maturation by retrograde transport. Incoming cargo is modified by Golgi enzymes and then lipid partitioning separates cargo from enzymes (divergent arrows). Intra-Golgi transport could be controlled via COPI vesicles that regulate the composition and concentration of SNARE proteins and lipids in the cisternae. During anterograde transport the cargo molecules are maintained within a cisterna that changes identity by the retrograde recycling of SNAREs, Golgi resident proteins, and lipids via intercisternal tubules, with the COG complex acting as a tethering factor. Arf1 is present across the Golgi and regulates COPI vesicle formation but distinct domains are conferred by the ArfGEFs and ArfGAPs, all of which associate and dissociate rapidly from the Golgi membranes according to the changing lipid/protein identity (see text for details).