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Osh4p is needed to reduce the level of phosphatidylinositol-4-phosphate on secretory vesicles as they mature.

Ling Y, Hayano S, Novick P - Mol. Biol. Cell (2014)

Bottom Line: Phosphatidylinositol-4-phosphate (PI4P) is produced on both the Golgi and the plasma membrane.We show here that in yeast the oxysterol-binding proteins Osh1-Osh7 are collectively needed to maintain the normal distribution of PI4P and that Osh4p is critical in this function.This reduction in PI4P is necessary for a switch in the regulation of the Sec4p exchange protein, Sec2p, from an interaction with the upstream Rab, Ypt31/32, to an interaction with a downstream Sec4p effector, Sec15p.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.

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A model for Osh4's role in regulating PI4P during secretion. Osh4 is recruited to the secretory vesicles through PI4P binding (and possibly through protein–protein interactions as well). Osh4 negatively regulates PI4P levels on the secretory vesicles and thereby enhances the Sec2–Sec15 interaction during this process. Finally, Osh4 leaves the secretory vesicles once PI4P levels are reduced below a certain threshold.
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Figure 7: A model for Osh4's role in regulating PI4P during secretion. Osh4 is recruited to the secretory vesicles through PI4P binding (and possibly through protein–protein interactions as well). Osh4 negatively regulates PI4P levels on the secretory vesicles and thereby enhances the Sec2–Sec15 interaction during this process. Finally, Osh4 leaves the secretory vesicles once PI4P levels are reduced below a certain threshold.

Mentions: In total, we propose that Osh4p is the principal Osh protein controlling the PI4P level of secretory vesicles. As the secretory vesicles move from Golgi to the plasma membrane, PI4P is turned over and/or extracted under the control of Osh4p (Figure 7). The decrease in the level of PI4P may facilitate the release of Ypt32p and recruitment of Sec15p to secretory vesicles. This mechanism is important for the subsequent assembly of exocyst and tethering of secretory vesicles in preparation for fusion to the plasma membrane.


Osh4p is needed to reduce the level of phosphatidylinositol-4-phosphate on secretory vesicles as they mature.

Ling Y, Hayano S, Novick P - Mol. Biol. Cell (2014)

A model for Osh4's role in regulating PI4P during secretion. Osh4 is recruited to the secretory vesicles through PI4P binding (and possibly through protein–protein interactions as well). Osh4 negatively regulates PI4P levels on the secretory vesicles and thereby enhances the Sec2–Sec15 interaction during this process. Finally, Osh4 leaves the secretory vesicles once PI4P levels are reduced below a certain threshold.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4214785&req=5

Figure 7: A model for Osh4's role in regulating PI4P during secretion. Osh4 is recruited to the secretory vesicles through PI4P binding (and possibly through protein–protein interactions as well). Osh4 negatively regulates PI4P levels on the secretory vesicles and thereby enhances the Sec2–Sec15 interaction during this process. Finally, Osh4 leaves the secretory vesicles once PI4P levels are reduced below a certain threshold.
Mentions: In total, we propose that Osh4p is the principal Osh protein controlling the PI4P level of secretory vesicles. As the secretory vesicles move from Golgi to the plasma membrane, PI4P is turned over and/or extracted under the control of Osh4p (Figure 7). The decrease in the level of PI4P may facilitate the release of Ypt32p and recruitment of Sec15p to secretory vesicles. This mechanism is important for the subsequent assembly of exocyst and tethering of secretory vesicles in preparation for fusion to the plasma membrane.

Bottom Line: Phosphatidylinositol-4-phosphate (PI4P) is produced on both the Golgi and the plasma membrane.We show here that in yeast the oxysterol-binding proteins Osh1-Osh7 are collectively needed to maintain the normal distribution of PI4P and that Osh4p is critical in this function.This reduction in PI4P is necessary for a switch in the regulation of the Sec4p exchange protein, Sec2p, from an interaction with the upstream Rab, Ypt31/32, to an interaction with a downstream Sec4p effector, Sec15p.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.

Show MeSH
Related in: MedlinePlus