The yeast synaptojanin-like proteins control the cellular distribution of phosphatidylinositol (4,5)-bisphosphate.
The yeast synaptojanin-like proteins control the cellular distribution of phosphatidylinositol (4,5)-bisphosphate.
复制标题
酵母突触素样蛋白控制磷脂酰肌醇 (4,5)-二磷酸的细胞分布。
DOI：
10.1091/mbc.01-10-0476
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发表时间：
2002
影响因子：
3.3
通讯作者：
Emr,ScottD
中科院分区：
文献类型：
--
作者：
Stefan,ChristopherJ;Audhya,Anjon;Emr,ScottD
磷脂酰肌醇（PI）是由特定的激酶，磷酸酶和脂肪酶，确保在不同的膜上的离散PI亚型的适当定位合成和翻转。我们分析了酵母synaptojanin样蛋白的作用，使用一个菌株，只表达一个温度条件等位基因的SJL 2。我们的分析表明，酵母synaptojanins的失活导致增加的细胞水平的磷脂酰肌醇（3，5）-二磷酸和磷脂酰肌醇（4，5）-二磷酸（PtdIns（4，5）P 2），伴随着缺陷的肌动蛋白组织，内吞作用，网格蛋白介导的高尔基体和内体之间的排序。在synaptojanin缺陷细胞中观察到的表型与PtdIns（4，5）P2的积累相关，因为这些效应被MSS 4突变或仅具有PI 5-磷酸酶活性的Sjl 2 p突变形式所拯救。我们利用具有不同PI结合特异性的绿色荧光蛋白-普列克底物蛋白同源结构域嵌合体（称为荧光脂质相关报告分子的FLARE）来可视化酵母中PtdIns（4，5）P2和磷脂酰肌醇4-磷酸的池。PtdIns（4，5）P2以依赖于Mss 4p活性的方式定位于质膜。失活的酵母synaptojanins，PtdIns（4，5）P2积累在细胞内室，以及细胞表面。与此相反，Pik 1 p产生的磷脂酰肌醇4-磷酸定位于细胞内室。综上所述，我们的研究结果表明酵母synaptojanins控制PtdIns（4，5）P2在体内的定位，并为不同PI种类的区室化提供了进一步的证据。
Phosphoinositides (PI) are synthesized and turned over by specific kinases, phosphatases, and lipases that ensure the proper localization of discrete PI isoforms at distinct membranes. We analyzed the role of the yeast synaptojanin-like proteins using a strain that expressed only a temperature-conditional allele of SJL2. Our analysis demonstrated that inactivation of the yeast synaptojanins leads to increased cellular levels of phosphatidylinositol (3, 5)-bisphosphate and phosphatidylinositol (4, 5)-bisphosphate (PtdIns (4, 5) P 2), accompanied by defects in actin organization, endocytosis, and clathrin-mediated sorting between the Golgi and endosomes. The phenotypes observed in synaptojanin-deficient cells correlated with accumulation of PtdIns (4, 5) P 2, because these effects were rescued by mutations in MSS4or a mutant form of Sjl2p that harbors only PI 5-phosphatase activity. We utilized green fluorescent protein-pleckstrin homology domain chimeras (termed FLAREs for fluorescent lipid-associated reporters) with distinct PI-binding specificities to visualize pools of PtdIns (4, 5) P 2 and phosphatidylinositol 4-phosphate in yeast. PtdIns (4, 5) P 2 localized to the plasma membrane in a manner dependent on Mss4p activity. On inactivation of the yeast synaptojanins, PtdIns (4, 5) P 2 accumulated in intracellular compartments, as well as the cell surface. In contrast, phosphatidylinositol 4-phosphate generated by Pik1p localized in intracellular compartments. Taken together, our results demonstrate that the yeast synaptojanins control the localization of PtdIns (4, 5) P 2 in vivo and provide further evidence for the compartmentalization of different PI species.