Multilamellar endosome-like compartment accumulates in the yeast vps28 vacuolar protein sorting mutant
Multilamellar endosome-like compartment accumulates in the yeast vps28 vacuolar protein sorting mutant
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DOI：
10.1091/mbc.7.6.985
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发表时间：
1996-06-01
影响因子：
3.3
通讯作者：
Emr, SD
中科院分区：
文献类型：
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作者：
Rieder, SE;Banta, LM;Emr, SD
在酿酒酵母中，羧肽酶 Y 等液泡蛋白通过内体样中间室从高尔基体转移到溶酶体样液泡。液泡蛋白分选 (vps) 突变体 vps28 是“E 类”vps 突变体的成员，在异常的 E 类内体样区室中积累液泡、内吞和晚期高尔基体标记。 VPS28 的序列分析揭示了一个开放阅读框，预计编码 242 个氨基酸的亲水蛋白。与此一致的是，针对 Vps28p 产生的多克隆抗血清识别出 28 kDa 的细胞质蛋白。 VPS28 的破坏导致前往液泡的生物合成运输和内吞运输出现中度缺陷。在 vps28 无效突变细胞中，可溶性液泡水解酶向液泡的转运受到损害（类似于 40-50% 羧肽酶 Y 错配）。内吞标记物 FM 4-64（一种重要的亲脂性染料）的内化导致 Delta vps28 细胞中邻近扩大的液泡的小细胞内区室被强烈染色。此外，液泡H+-ATP酶在Delta vps28细胞的液泡周围E类区室中积累，从质膜内化的a因子受体Ste3p也是如此。电子显微镜分析显示存在一个由弯曲膜池堆叠组成的新型隔室。免疫定位研究表明，液泡 H+-ATP 酶与杯状脑池结构相关，表明它对应于荧光显微镜观察到的 E 类隔室。我们的数据表明，vps28突变体中从前液泡区室顺行和逆行运输的动力学缺陷导致蛋白质和膜在夸大的多层内体区室中积累。我们认为，Vps28p 以及其他 E 类 Vps 蛋白可能促进（可能作为外壳蛋白）有效转运出液泡前内体所需的转运中间体的形成。
In the yeast Saccharomyces cerevisiae, vacuolar proteins such as carboxypeptidase Y transit from the Golgi to the lysosome-like vacuole via an endosome-like intermediate compartment. the vacuolar protein sorting (vps) mutant vps28, a member of the ''class E'' vps mutants, accumulates vacuolar, endocytic, and late Golgi markers in an aberrant endosome-like class E compartment. Sequence analysis of VPS28 revealed an open reading frame predicted to encode a hydrophilic protein of 242 amino acids. Consistent with this, polyclonal antiserum raised against Vps28p recognized a cytoplasmic protein of 28 kDa. Disruption of VPS28 resulted in moderate defects in both biosynthetic traffic and endocytic traffic destined for the vacuole. The transport of soluble vacuolar hydrolases to the vacuole was impaired in vps28 null mutant cells (similar to 40-50% carboxypeptidase Y missorted). Internalization of the endocytic marker FM 4-64, a vital lipophilic dye, resulted in intense staining of a small intracellular compartment adjacent to an enlarged vacuole in Delta vps28 cells. Furthermore, the vacuolar H+-ATPase accumulated in the perivacuolar class E compartment in Delta vps28 cells, as did a-factor receptor Ste3p that was internalized from the plasma membrane. Electron microscopic analysis revealed the presence of a novel compartment consisting of stacks of curved membrane cisternae. Immunolocalization studies demonstrated that the vacuolar H+-ATPase is associated with this cupped cisternal structure, indicating that it corresponds to the class E compartment observed by fluorescence microscopy. Our data indicate that kinetic defects in both anterograde and retrograde transport out of the prevacuolar compartment in vps28 mutants result in the accumulation of protein and membrane in an exaggerated multilamellar endosomal compartment. We propose that Vps28p, as well as other class E Vps proteins, may facilitate (possibly as coat proteins) the formation of transport intermediates required for efficient transport out of the prevacuolar endosome.