THE YEAST CA-2+-ATPASE HOMOLOG, PMR1, IS REQUIRED FOR NORMAL GOLGI FUNCTION AND LOCALIZES IN A NOVEL GOLGI-LIKE DISTRIBUTION
THE YEAST CA-2+-ATPASE HOMOLOG, PMR1, IS REQUIRED FOR NORMAL GOLGI FUNCTION AND LOCALIZES IN A NOVEL GOLGI-LIKE DISTRIBUTION
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DOI：
10.1091/mbc.3.6.633
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发表时间：
1992-06-01
影响因子：
3.3
通讯作者：
FINK, GR
中科院分区：
文献类型：
--
作者：
ANTEBI, A;FINK, GR
PMR1 是酿酒酵母中的一种 Ca2+-三磷酸腺苷酶 (ATPase) 同源物，定位于一种新型高尔基体样细胞器。与高尔基体定位一致，在亚细胞分离实验中，大部分 PMR1 与高尔基体标记物共迁移，并且通过间接免疫荧光对 PMR1 进行染色，显示出类似于酵母中高尔基体染色的点状图案。然而，在双标记免疫荧光实验中，PMR1 仅显示与已知高尔基体标记 KEX2 和 SEC7 部分共定位。 PMR1 对高尔基体功能的影响表现为 pmr1 突变体中各种高尔基体过程的多效性缺陷，包括前 α 因子的蛋白水解加工受损和转化酶的不完整外链糖基化。与 PMR1 作为 Ca2+ 泵的提议作用一致，这些缺陷可以通过添加毫摩尔水平的细胞外 Ca2+ 来逆转，这表明 Ca2+ 的配置对于正常高尔基体功能至关重要。 PMR1 功能的缺失部分抑制了几种 sec 突变体的温度敏感生长缺陷，而 PMR1 的过度表达则限制了其他突变体的生长。其中一些相互作用是通过外部 Ca2+ 浓度的变化来调节的。这些结果表明 Ca2+ 在控制分泌途径运输和加工的成分的正常功能中发挥着全局作用。
PMR1, a Ca2+-adenosine triphosphatase (ATPase) homologue in the yeast Saccharomyces cerevisiae localizes to a novel Golgi-like organelle. Consistent with a Golgi localization, the bulk of PMR1 comigrates with Golgi markers in subcellular fractionation experiments, and staining of PMR1 by indirect immunofluorescence reveals a punctate pattern resembling Golgi staining in yeast. However, PMR1 shows only partial colocalization with known Golgi markers, KEX2 and SEC7, in double-label immunofluorescence experiments. The effect of PMR1 on Golgi function is indicated by pleiotropic defects in various Golgi processes in pmr1 mutants, including impaired proteolytic processing of pro-alpha factor and incomplete outer chain glycosylation of invertase. Consistent with the proposed role of PMR1 as a Ca2+ pump, these defects are reversed by the addition of millimolar levels of extracellular Ca2+, suggesting that Ca2+ disposition is essential to normal Golgi function. Absence of PMR1 function partially suppresses the temperature-sensitive growth defects of several sec mutants, and overexpression of PMR1 restricts the growth of others. Some of these interactions are modulated by changes in external Ca2+ concentrations. These results imply a global role for Ca2+ in the proper function of components governing transit and processing through the secretory pathway.