The Saccharomyces cerevisiae spindle pole body (SPB) component Nbp1p is required for SPB membrane insertion and interacts with the integral membrane proteins Ndc1p and Mps2p
The Saccharomyces cerevisiae spindle pole body (SPB) component Nbp1p is required for SPB membrane insertion and interacts with the integral membrane proteins Ndc1p and Mps2p
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DOI：
10.1091/mbc.e05-07-0668
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发表时间：
2006-04-01
影响因子：
3.3
通讯作者：
Winey, M
中科院分区：
文献类型：
--
作者：
Araki, Y;Lau, CK;Winey, M
酿酒酵母中的纺锤体极体（SPB）具有成核和组织纺锤体微管的功能，在酵母的整个生命周期中，SPB都嵌入核被膜中。然而，SPB的膜插入机制尚未阐明。Ndc 1 p是一种定位于SPB的膜蛋白，在SPB复制过程中，它是SPB插入核膜所必需的。为了更好地了解Ndc 1 p的功能，我们使用Ndcl-39温度敏感等位基因进行了剂量抑制筛选。我们确定了一个重要的SPB组件，Nbp 1 p。NBP 1显示除了NDC 1之外还与几个SPB基因遗传相互作用，并且双杂交分析显示Nbp 1 p与Ndc 1 p结合。此外，Nbp 1 p位于SPB中的Mps 2 p-Bbp 1 p复合物中。免疫电子显微镜证实，Nbp 1 p定位于SPB，这表明在这个位置的功能。与此假设一致，nbp 1-td（降解决定子等位基因）细胞在耗尽Nbp 1 p后SPB复制失败。重要的是，这些细胞表现出“死亡”SPB表型，类似于MPS 2、NDC 1或BBP 1中的细胞突变体。这些结果表明，Nbp 1 p是一个SPB的组成部分，在SPB插入到核膜的点在SPB复制的行为。
The spindle pole body (SPB) in Saccharomyces cerevisiae functions to nucleate and organize spindle microtubules, and it is embedded in the nuclear envelope throughout the yeast life cycle. However, the mechanism of membrane insertion of the SPB has not been elucidated. Ndc1p is an integral membrane protein that localizes to SPBs, and it is required for insertion of the SPB into the nuclear envelope during SPB duplication. To better understand the function of Ndc1p, we performed a dosage suppressor screen using the ndcl-39 temperature-sensitive allele. We identified an essential SPB component, Nbp1p. NBP1 shows genetic interactions with several SPB genes in addition to NDC1, and two-hybrid analysis revealed that Nbp1p binds to Ndc1p. Furthermore, Nbp1p is in the Mps2p-Bbp1p complex in the SPB. Immunoelectron microscopy confirmed that Nbp1p localizes to the SPB, suggesting a function at this location. Consistent with this hypothesis, nbp1-td (a degron allele) cells fail in SPB duplication upon depletion of Nbp1p. Importantly, these cells exhibit a "dead" SPB phenotype, similar to cells mutant in MPS2, NDC1, or BBP1. These results demonstrate that Nbp1p is a SPB component that acts in SPB duplication at the point of SPB insertion into the nuclear envelope.