Tubulation of Golgi membranes in vivo and in vitro in the absence of brefeldin A.

Abstract

Abstract. Recent in vivo studies with the fungal metabolite, brefeldin A (BFA), have shown that in the absence of vesicle formation, membranes of the Golgi complex and the trans-Golgi network (TGN) are nevertheless able to extend long tubules which fuse with selected target organelles. We report here that the ability to form tubules (>7 #m long) could be reproduced in vitro by treatment of isolated, intact Golgi membranes with BFA under certain conditions. Surprisingly, an even more impressive degree of tubulation could be achieved by incubating Golgi stacks with an ATP-reduced cytosolic fraction, without any BFA at all. Similarly, tubulation of Golgi membranes in vivo occurred after treatment of cells with intermediate levels of NaN3 and 2-deoxyglucose. The formarion of tubules in vitro, either by BFA treatment or low-ATP cytosol, correlated precisely with a loss of the vesicle-associated coat protein ~/-COP from Golgi membranes. After removal of BFA or addition of ATE membrane tubules served as substrates for the rebinding of/3-COP and for the formation of vesicles in vitro. These results provide support for the idea that a reciprocal relationship exists between tubulation and vesiculation (Klausner, R. D., J. G. Donaldson, and J. Lippincott-Schwartz. 1992. J. Cell Biol. 116:1071-1080. Moreover, they show that tubulation is an inherent property of Golgi membranes, since it occurs without the aid of microtubules or BFA treatment. Finally the results indicate the presence of cytosolic factors, independent of vesicle-associated coat proteins, that mediate the budding/tubulation of Golgi membranes.

Retrograde Transport from the Pre-Golgi Intermediate Compartment and the Golgi Complex Is Affected by the Vacuolar H+-ATPase Inhibitor Bafilomycin A1

“…When the formation of COPI vesicles (caused by lack of coatomer binding) is inhibited by brefeldin A (BFA), long tubules extend from the Golgi and fuse with the ER (Lippincott- . Similar Golgi tubules also form in vitro in the absence of BFA (Cluett et al, 1993;Weidman et al, 1993), and recent studies of Golgi dynamics in living cells support the idea that they function as intermediates in retrograde Golgi-to-ER transport (Sciaky et al, 1997). In unperturbed cells, the formation of long tubules could be restricted by an efficient vesiculation process (Klausner et al, 1992).…”

The cytosolic chaperone α-Crystallin B rescues appropriate folding and compartmentalization of misfolded multispan transmembrane proteins

“…It is well established that BFA induces Golgi tubulation and fusion with the ER, thus blocking in the ER the protein destined to the PM (Cluett et al, 1993;Lippincott-Schwartz et al, 1989;Lippincott-Schwartz et al, 1990). As shown in supplementary material Fig.…”

Sequential deposition of plant glycoproteins and polysaccharides at the host-parasite interface ofUromyces vignae andVigna sinensis

“…Perhaps the "pinching off" process is somewhat delayed around haustoria or differs from the usual process. Many fungi produce the macrocyclic lacton Brefeldin A which induces tubulation of Golgi membranes (Cluett et al 1993). Rust fungi also seem to be able to induce tubule-formation at the extrahaustorial membrane.…”