Matrix proteins can generate the higher order architecture of the Golgi apparatus

Abstract

The Golgi apparatus in animal cells comprises a reticulum of linked stacks in the pericentriolar and often in the juxtanuclear regions of the cell. The unique architecture of this organelle is thought to depend on the cytoskeleton and cytoplasmic matrix proteins--the best characterized being the golgin family of fibrous, coiled-coil proteins and the GRASP family of stacking proteins. Here we show that these matrix proteins can be separated from oligosaccharide-modifying enzymes in the Golgi stack without affecting their ability to form a ribbon-like reticulum in the correct location near to the nucleus. Our data suggest that the Golgi is a structural scaffold that can exist independently of, but is normally populated by, the enzyme-containing membranes that modify transiting cargo. This new concept of the Golgi further indicates that the Golgi may be an autonomous organelle rather than one that is in simple dynamic equilibrium with the endoplasmic reticulum.

Bap31 Is an Itinerant Protein That Moves between the Peripheral Endoplasmic Reticulum (ER) and a Juxtanuclear Compartment Related to ER-associated Degradation

“…GM130 is one of the fast-moving proteins during BFA recovery (Jiang et al, 2006). As reported previously (Nakamura et al, 1995;Seemann et al, 2000;Ward et al, 2001), GM130 was distributed in punctate structures in BFA-treated cells (Supplemental Figure S3, second row). Although previous studies showed that combined treatment of normal rat kidney or HeLa cells with BFA followed by BFA plus H89 causes ER localization of GM130 (Puri and Linstedt, 2003;Jiang et al, 2006), such redistribution was not observed in COS-7 cells when 50 M H89 in addition to 10 M BFA was used (data not shown).…”

TNO1 Is Involved in Salt Tolerance and Vacuolar Trafficking in Arabidopsis

“…8). A similar effect was observed for the mammalian golgin GM130, which, unlike most Golgi proteins, does not relocate to the ER in the presence of BFA (Seemann et al, 2000). GM130 is a tethering factor that also interacts with SNAREs during vesicle fusion and a Golgi matrix protein required for the integrity of the Golgi structure (Diao et al, 2008).…”

“…GM130 is a tethering factor that also interacts with SNAREs during vesicle fusion and a Golgi matrix protein required for the integrity of the Golgi structure (Diao et al, 2008). After BFA treatment, GM130 remains in a Golgi remnant, while Golgi luminal proteins are transported back to the ER, indicating that GM130 is involved in maintaining Golgi structure (Seemann et al, 2000). Although there is no sequence homology between TNO1 and GM130, based on the properties of TNO1, it is possible that TNO1 also functions as a tethering factor and is involved in maintaining TGN structure or identity.…”

Mitogen-activated Protein Kinase Kinase 1-dependent Golgi Unlinking Occurs in G2Phase and Promotes the G2/M Cell Cycle Transition

“…As a positive control, the phospho-ERK/ERK2 ratio is also shown for cells treated with U0126 for 30 min before the buffer challenges. Schwartz et al, 1989;Peyroche et al, 1999;Seemann et al, 2000). Strikingly, treatment of cells with BFA abrogated the 2-h delay caused by either MEK1-knockdown ( Figure 2D) or U0126 treatment ( Figure 2E).…”