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Traffic through the Golgi apparatus.

Pelham HR - J. Cell Biol. (2001)

Bottom Line: Large forms of cargo such as protein aggregates are thought to progress through the Golgi stack by a process of cisternal maturation, balanced by a return flow of Golgi resident proteins in COPI-coated vesicles.Two papers (Martínez-Menárguez et al., 2001; Mironov et al., 2001, this issue) use sophisticated light and electron microscopy to provide evidence that the vesicular stomatitis virus membrane glycoprotein (VSV G)* is largely excluded from vesicles in vivo, and does not move between cisternae, whereas resident Golgi enzymes freely enter vesicles as predicted by the cisternal maturation model.Both papers conclude that vesicles are likely to play only a minor role in the anterograde transport of cargo through the Golgi apparatus in mammalian tissue culture cells.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Biology, Medical Research Council, Hills Road, Cambridge CB2 2QH, UK. hp@mrc-lmb.cam.ac.uk

ABSTRACT
The role of vesicles in cargo transport through the Golgi apparatus has been controversial. Large forms of cargo such as protein aggregates are thought to progress through the Golgi stack by a process of cisternal maturation, balanced by a return flow of Golgi resident proteins in COPI-coated vesicles. However, whether this is the primary role of vesicles, or whether they also serve to transport small cargo molecules in a forward direction has been debated. Two papers (Martínez-Menárguez et al., 2001; Mironov et al., 2001, this issue) use sophisticated light and electron microscopy to provide evidence that the vesicular stomatitis virus membrane glycoprotein (VSV G)* is largely excluded from vesicles in vivo, and does not move between cisternae, whereas resident Golgi enzymes freely enter vesicles as predicted by the cisternal maturation model. Both papers conclude that vesicles are likely to play only a minor role in the anterograde transport of cargo through the Golgi apparatus in mammalian tissue culture cells.

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Schematic structure of the Golgi. The Golgi ribbon consists of cisternal stacks separated by tubulovesicular domains (gray boxes). Tubular connections between equivalent cisternae are well documented (Ladinsky et al., 1999); whether cisternae at different levels are also sometimes connected by tubules is less clear. Individual glycosyltransferases tend to be found at a characteristic level of the stack (red). They enter vesicles and seem to be able to move along the ribbon. When VSV G is delivered to the Golgi in a short pulse, it enters only a subset of the stacks (Mironov et al., 2001). Single cisternae containing VSV G (green) can then move through the stack; exclusion of VSV G from the tubulovesicular regions prevents its transfer both to adjacent cisternae in the same stack and to other stacks in the ribbon. Blue arrows indicate forward movement of cisternae and presumed net retrograde movement in the tubulovesicular regions.
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fig1: Schematic structure of the Golgi. The Golgi ribbon consists of cisternal stacks separated by tubulovesicular domains (gray boxes). Tubular connections between equivalent cisternae are well documented (Ladinsky et al., 1999); whether cisternae at different levels are also sometimes connected by tubules is less clear. Individual glycosyltransferases tend to be found at a characteristic level of the stack (red). They enter vesicles and seem to be able to move along the ribbon. When VSV G is delivered to the Golgi in a short pulse, it enters only a subset of the stacks (Mironov et al., 2001). Single cisternae containing VSV G (green) can then move through the stack; exclusion of VSV G from the tubulovesicular regions prevents its transfer both to adjacent cisternae in the same stack and to other stacks in the ribbon. Blue arrows indicate forward movement of cisternae and presumed net retrograde movement in the tubulovesicular regions.

Mentions: The mammalian Golgi typically consists of a ribbon-like structure in which stacks of cisternae alternate with regions rich in COPI-coated vesicles and tubules (Fig. 1). Early studies in a variety of systems suggested that large structures, such as algal scales and collagen aggregates, are restricted to cisternal membranes and proceed through Golgi stacks by a process of maturation, in which new cisternae form on the cis side of the stack, whereas mature ones fragment and peel off the trans side. With the realization that the Golgi contains many resident proteins such as glycosyltransferases, a retrograde transport role was invoked for the vesicles to explain how these enzymes managed to stay in place on the escalator system (Martínez-Menárguez et al., 2001, this issue).


Traffic through the Golgi apparatus.

Pelham HR - J. Cell Biol. (2001)

Schematic structure of the Golgi. The Golgi ribbon consists of cisternal stacks separated by tubulovesicular domains (gray boxes). Tubular connections between equivalent cisternae are well documented (Ladinsky et al., 1999); whether cisternae at different levels are also sometimes connected by tubules is less clear. Individual glycosyltransferases tend to be found at a characteristic level of the stack (red). They enter vesicles and seem to be able to move along the ribbon. When VSV G is delivered to the Golgi in a short pulse, it enters only a subset of the stacks (Mironov et al., 2001). Single cisternae containing VSV G (green) can then move through the stack; exclusion of VSV G from the tubulovesicular regions prevents its transfer both to adjacent cisternae in the same stack and to other stacks in the ribbon. Blue arrows indicate forward movement of cisternae and presumed net retrograde movement in the tubulovesicular regions.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199341&req=5

fig1: Schematic structure of the Golgi. The Golgi ribbon consists of cisternal stacks separated by tubulovesicular domains (gray boxes). Tubular connections between equivalent cisternae are well documented (Ladinsky et al., 1999); whether cisternae at different levels are also sometimes connected by tubules is less clear. Individual glycosyltransferases tend to be found at a characteristic level of the stack (red). They enter vesicles and seem to be able to move along the ribbon. When VSV G is delivered to the Golgi in a short pulse, it enters only a subset of the stacks (Mironov et al., 2001). Single cisternae containing VSV G (green) can then move through the stack; exclusion of VSV G from the tubulovesicular regions prevents its transfer both to adjacent cisternae in the same stack and to other stacks in the ribbon. Blue arrows indicate forward movement of cisternae and presumed net retrograde movement in the tubulovesicular regions.
Mentions: The mammalian Golgi typically consists of a ribbon-like structure in which stacks of cisternae alternate with regions rich in COPI-coated vesicles and tubules (Fig. 1). Early studies in a variety of systems suggested that large structures, such as algal scales and collagen aggregates, are restricted to cisternal membranes and proceed through Golgi stacks by a process of maturation, in which new cisternae form on the cis side of the stack, whereas mature ones fragment and peel off the trans side. With the realization that the Golgi contains many resident proteins such as glycosyltransferases, a retrograde transport role was invoked for the vesicles to explain how these enzymes managed to stay in place on the escalator system (Martínez-Menárguez et al., 2001, this issue).

Bottom Line: Large forms of cargo such as protein aggregates are thought to progress through the Golgi stack by a process of cisternal maturation, balanced by a return flow of Golgi resident proteins in COPI-coated vesicles.Two papers (Martínez-Menárguez et al., 2001; Mironov et al., 2001, this issue) use sophisticated light and electron microscopy to provide evidence that the vesicular stomatitis virus membrane glycoprotein (VSV G)* is largely excluded from vesicles in vivo, and does not move between cisternae, whereas resident Golgi enzymes freely enter vesicles as predicted by the cisternal maturation model.Both papers conclude that vesicles are likely to play only a minor role in the anterograde transport of cargo through the Golgi apparatus in mammalian tissue culture cells.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Biology, Medical Research Council, Hills Road, Cambridge CB2 2QH, UK. hp@mrc-lmb.cam.ac.uk

ABSTRACT
The role of vesicles in cargo transport through the Golgi apparatus has been controversial. Large forms of cargo such as protein aggregates are thought to progress through the Golgi stack by a process of cisternal maturation, balanced by a return flow of Golgi resident proteins in COPI-coated vesicles. However, whether this is the primary role of vesicles, or whether they also serve to transport small cargo molecules in a forward direction has been debated. Two papers (Martínez-Menárguez et al., 2001; Mironov et al., 2001, this issue) use sophisticated light and electron microscopy to provide evidence that the vesicular stomatitis virus membrane glycoprotein (VSV G)* is largely excluded from vesicles in vivo, and does not move between cisternae, whereas resident Golgi enzymes freely enter vesicles as predicted by the cisternal maturation model. Both papers conclude that vesicles are likely to play only a minor role in the anterograde transport of cargo through the Golgi apparatus in mammalian tissue culture cells.

Show MeSH
Related in: MedlinePlus