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. Author manuscript; available in PMC: 2014 Jun 1.
Published in final edited form as: Trends Cell Biol. 2013 Feb 28;23(6):296–304. doi: 10.1016/j.tcb.2013.01.008

Fig. 1. GRASPs and golgins in Golgi stacking and ribbon linking during the cell cycle.

Fig. 1

A. GRASP65 (locates to cis-Golgi) and GRASP55 (locates to medial-to-trans-Golgi) homodimers on adjacent membranes form trans-oligomerizers, bring the membrane closer to each other to (a) form stacks when GRASPs localize between the cisternae, and to (b) form a ribbon when GRASPs are at the rims of the Golgi stacks. In addition to GRASPs, golgins are also required for the maintenance of Golgi ribbon integrity by either (c) tethering vesicles/transport carriers to Golgi membranes, such as GM130, or by (d) tethering membranes from neighboring stacks, as GMAP210.

B. During mitosis, GRASPs and GM130 are phosphorylated by mitotic kinases, which disrupts their oligomerization and allows ribbon unlinking and cisternae unstacking.

C. The resulting single cisternae by unstacking undergo continuous vesicle budding to further disassemble Golgi membranes into vesicles and tubular structures. In cells, Golgi ribbon unlinking occurs in G2 phase, while Golgi unstacking and vesiculation take place in prophase and prometaphase. The reverse processes, Golgi membrane fusion, stacking and ribbon linking, occur in telophase and cytokinesis.