Yeast Kex1p is a Golgi-associated membrane protein: deletions in a cytoplasmic targeting domain result in mislocalization to the vacuolar membrane.
Yeast Kex1p is a Golgi-associated membrane protein: deletions in a cytoplasmic targeting domain result in mislocalization to the vacuolar membrane.
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DOI：
10.1083/jcb.119.6.1459
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发表时间：
1992-12
期刊：
影响因子：
--
通讯作者：
Bussey H
中科院分区：
文献类型：
--
作者：
Cooper A;Bussey H
我们研究了Kex1p的定位，Kex1p是一种I型跨膜羧肽酶，参与酵母分泌途径中的前体加工。间接免疫荧光表明，Kex1p存在于类似酵母高尔基体的点状细胞器中，由Kex2p和Sec7p鉴定（Franzusoff, a .， K. Redding， J. Crosby， R. S. Fuller和R. Schekman, 1991）。细胞生物学杂志。112:27- 37)。Kex1p的糖基化研究与高尔基定位一致，因为Kex1p以MNN1依赖的方式逐渐n -糖基化。为了解决Kex1p靶向高尔基体的基础，我们检查了该蛋白的一系列羧基端截断的细胞位置。结果表明，细胞质上暴露的羧基末端结构域是该膜蛋白在高尔基体内保留所必需的。保留区缺失或野生型Kex1p的过量产生导致Kex1p在液泡膜上的错误定位。这一意想不到的发现是根据液泡作为膜蛋白的默认目的地的模型来讨论的，或者是在液泡默认定位到质膜后对液泡的内吞作用。
We have investigated the localization of Kex1p, a type I transmembrane carboxypeptidase involved in precursor processing within the yeast secretory pathway. Indirect immunofluorescence demonstrated the presence of Kex1p in a punctate organelle resembling the yeast Golgi apparatus as identified by Kex2p and Sec7p (Franzusoff, A., K. Redding, J. Crosby, R. S. Fuller, and R. Schekman. 1991. J. Cell Biol. 112:27- 37). Glycosylation studies of Kex1p were consistent with a Golgi location, as Kex1p was progressively N-glycosylated in an MNN1- dependent manner. To address the basis of Kex1p targeting to the Golgi apparatus, we examined the cellular location of a series of carboxy- terminal truncations of the protein. The results indicate that a cytoplasmically exposed carboxy-terminal domain is required for retention of this membrane protein within the Golgi apparatus. Deletions of the retention region or overproduction of wild-type Kex1p led to mislocalization of Kex1p to the vacuolar membrane. This unexpected finding is discussed in terms of models involving either the vacuole as a default destination for membrane proteins, or by endocytosis to the vacuole following their default localization to the plasma membrane.