Publication Date:
2014-02-28
Description:
Sac1 is a phosphoinositide phosphatase, which preferentially dephosphorylates phosphatidylinositol 4-phosphate. Mutation of SAC1 causes not only accumulation of phosphoinositides, but also reduction of the phosphatidylserine (PS) level in yeast Saccharomyces cerevisiae . In this study, we characterized the mechanism underlying the PS reduction in SAC1 -deleted cells. Incorporation of 32 P into PS was significantly delayed in sac1 ∆ cells. Such delay was also observed in SAC1 - and PS decarboxylase gene-deleted cells, suggesting that the reduction in the PS level is caused by reduction in the rate of biosynthesis of PS. A reduction in the PS level was also observed with repression of STT4 encoding phosphatidylinositol 4-kinase or deletion of VPS34 encoding phophatidylinositol 3-kinase. However, the combination of mutations of SAC1 and STT4 or VPS34 did not restore the reduced PS level, suggesting that both the synthesis and degradation of phosphoinositides are important for maintenance of the PS level. Finally, we observed an abnormal PS distribution in sac1∆ cells when a specific probe for PS was expressed. Collectively, these results suggested that Sac1 is involved in maintenance of a normal rate of biosynthesis and distribution of PS. This article is protected by copyright. All rights reserved.
Print ISSN:
0749-503X
Electronic ISSN:
1097-0061
Topics:
Biology
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