Figure 1.

Schematic representation of mitotic partitioning of the Golgi ribbon. This first step of mitotic Golgi fragmentation (i.e., ribbon unlinking) controls G2/M transition and requires the activities of BARS, GRASP55, and GRASP65. These processes also require the activities of several MAP kinase components, as indicated. At the onset of mitosis, these isolated stacks undergo further disassembly in the sequential steps of unstacking and vesiculation. These lead to the formation of the so-called “Golgi haze” during metaphase, where the Golgi membranes are completely fragmented. These processes require the activities of the kinases Plk1 and Cdc2, and their targets GRASP55 and GRASP65. Subsequent events result in dephosphorylation of the kinases that took part in the initial fragmentation, which leads to reassembly of the Golgi ribbon in the daughter cells.