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The Gcs1 and Age2 ArfGAP proteins provide overlapping essential function for transport from the yeast trans-Golgi network.

Poon PP, Nothwehr SF, Singer RA, Johnston GC - J. Cell Biol. (2001)

Bottom Line: Many intracellular vesicle transport pathways involve GTP hydrolysis by the ADP-ribosylation factor (ARF) type of monomeric G proteins, under the control of ArfGAP proteins.Here we show that the structurally related yeast proteins Gcs1 and Age2 form an essential ArfGAP pair that provides overlapping function for TGN transport.Our results demonstrate that the Gcs1 + Age2 ArfGAP pair provides overlapping function for transport from the TGN, and also indicate that multiple activities at the TGN can be maintained with the aid of a single ArfGAP.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7.

ABSTRACT
Many intracellular vesicle transport pathways involve GTP hydrolysis by the ADP-ribosylation factor (ARF) type of monomeric G proteins, under the control of ArfGAP proteins. Here we show that the structurally related yeast proteins Gcs1 and Age2 form an essential ArfGAP pair that provides overlapping function for TGN transport. Mutant cells lacking the Age2 and Gcs1 proteins cease proliferation, accumulate membranous structures resembling Berkeley bodies, and are unable to properly process and localize the vacuolar hydrolase carboxypeptidase (CPY) and the vacuolar membrane protein alkaline phosphatase (ALP), which are transported from the TGN to the vacuole by distinct transport routes. Immunofluorescence studies localizing the proteins ALP, Kex2 (a TGN resident protein), and Vps10 (the CPY receptor for transport from the TGN to the vacuole) suggest that inadequate function of this ArfGAP pair leads to a fragmentation of TGN, with effects on secretion and endosomal transport. Our results demonstrate that the Gcs1 + Age2 ArfGAP pair provides overlapping function for transport from the TGN, and also indicate that multiple activities at the TGN can be maintained with the aid of a single ArfGAP.

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Related in: MedlinePlus

Cells with inadequate Gcs1 + Age2 activity accumulate membranous structures. Cells were grown at 30°C or incubated at 37°C for 1 h before processing for electron microscopy. Shown is a representative section through a double-mutant cell processed after incubation at 37°C. The inset is a higher magnification of a region exhibiting membranous structures that resemble Berkeley bodies. Wild-type and single-mutant cells (and double-mutant cells at 30°C) did not display any such structures (unpublished data). In marked contrast, 50% of 113 random sections of double-mutant cells after growth at 37°C displayed these membranous structures.
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fig4: Cells with inadequate Gcs1 + Age2 activity accumulate membranous structures. Cells were grown at 30°C or incubated at 37°C for 1 h before processing for electron microscopy. Shown is a representative section through a double-mutant cell processed after incubation at 37°C. The inset is a higher magnification of a region exhibiting membranous structures that resemble Berkeley bodies. Wild-type and single-mutant cells (and double-mutant cells at 30°C) did not display any such structures (unpublished data). In marked contrast, 50% of 113 random sections of double-mutant cells after growth at 37°C displayed these membranous structures.

Mentions: Cells were examined by electron microscopy after incubation at 37°C. Wild-type cells and gcs1 and age2 single-mutant cells did not display any morphological indication of impaired vesicular transport (unpublished data), but the gcs1-3 age2 double-mutant cells incubated at 37°C contained obvious membranous structures (Fig. 4). These structures resembled the Berkeley bodies that were originally observed in cells harboring mutations such as sec7 or sec14, which impede membrane traffic through the Golgi apparatus, and these characteristic membranous structures are thought to be derived from Golgi compartments (Novick et al., 1980). Therefore, the altered morphology resulting from inadequate Gcs1 + Age2 activity may reflect impaired Golgi-related transport.


The Gcs1 and Age2 ArfGAP proteins provide overlapping essential function for transport from the yeast trans-Golgi network.

Poon PP, Nothwehr SF, Singer RA, Johnston GC - J. Cell Biol. (2001)

Cells with inadequate Gcs1 + Age2 activity accumulate membranous structures. Cells were grown at 30°C or incubated at 37°C for 1 h before processing for electron microscopy. Shown is a representative section through a double-mutant cell processed after incubation at 37°C. The inset is a higher magnification of a region exhibiting membranous structures that resemble Berkeley bodies. Wild-type and single-mutant cells (and double-mutant cells at 30°C) did not display any such structures (unpublished data). In marked contrast, 50% of 113 random sections of double-mutant cells after growth at 37°C displayed these membranous structures.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199332&req=5

fig4: Cells with inadequate Gcs1 + Age2 activity accumulate membranous structures. Cells were grown at 30°C or incubated at 37°C for 1 h before processing for electron microscopy. Shown is a representative section through a double-mutant cell processed after incubation at 37°C. The inset is a higher magnification of a region exhibiting membranous structures that resemble Berkeley bodies. Wild-type and single-mutant cells (and double-mutant cells at 30°C) did not display any such structures (unpublished data). In marked contrast, 50% of 113 random sections of double-mutant cells after growth at 37°C displayed these membranous structures.
Mentions: Cells were examined by electron microscopy after incubation at 37°C. Wild-type cells and gcs1 and age2 single-mutant cells did not display any morphological indication of impaired vesicular transport (unpublished data), but the gcs1-3 age2 double-mutant cells incubated at 37°C contained obvious membranous structures (Fig. 4). These structures resembled the Berkeley bodies that were originally observed in cells harboring mutations such as sec7 or sec14, which impede membrane traffic through the Golgi apparatus, and these characteristic membranous structures are thought to be derived from Golgi compartments (Novick et al., 1980). Therefore, the altered morphology resulting from inadequate Gcs1 + Age2 activity may reflect impaired Golgi-related transport.

Bottom Line: Many intracellular vesicle transport pathways involve GTP hydrolysis by the ADP-ribosylation factor (ARF) type of monomeric G proteins, under the control of ArfGAP proteins.Here we show that the structurally related yeast proteins Gcs1 and Age2 form an essential ArfGAP pair that provides overlapping function for TGN transport.Our results demonstrate that the Gcs1 + Age2 ArfGAP pair provides overlapping function for transport from the TGN, and also indicate that multiple activities at the TGN can be maintained with the aid of a single ArfGAP.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7.

ABSTRACT
Many intracellular vesicle transport pathways involve GTP hydrolysis by the ADP-ribosylation factor (ARF) type of monomeric G proteins, under the control of ArfGAP proteins. Here we show that the structurally related yeast proteins Gcs1 and Age2 form an essential ArfGAP pair that provides overlapping function for TGN transport. Mutant cells lacking the Age2 and Gcs1 proteins cease proliferation, accumulate membranous structures resembling Berkeley bodies, and are unable to properly process and localize the vacuolar hydrolase carboxypeptidase (CPY) and the vacuolar membrane protein alkaline phosphatase (ALP), which are transported from the TGN to the vacuole by distinct transport routes. Immunofluorescence studies localizing the proteins ALP, Kex2 (a TGN resident protein), and Vps10 (the CPY receptor for transport from the TGN to the vacuole) suggest that inadequate function of this ArfGAP pair leads to a fragmentation of TGN, with effects on secretion and endosomal transport. Our results demonstrate that the Gcs1 + Age2 ArfGAP pair provides overlapping function for transport from the TGN, and also indicate that multiple activities at the TGN can be maintained with the aid of a single ArfGAP.

Show MeSH
Related in: MedlinePlus