Nvj1p is the outer-nuclear-membrane receptor for oxysterol-binding protein homolog Osh1p in Saccharomyces cerevisiae
Nvj1p is the outer-nuclear-membrane receptor for oxysterol-binding protein homolog Osh1p in Saccharomyces cerevisiae
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DOI：
10.1242/jcs.01372
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发表时间：
2004-10-01
影响因子：
4
通讯作者：
Goldfarb, DS
中科院分区：
文献类型：
--
作者：
Kvam, E;Goldfarb, DS
OSH1 属于酵母中与哺乳动物氧甾醇结合蛋白 (OSBP) 相关的七成员基因家族。在这里，我们研究了 Osh1p 对酿酒酵母中核-液泡 (NV) 连接的靶向作用。 NV 连接是由核膜中的 Nvj1p 和液泡膜上的 Vac8p 介导的细胞器间界面。 Nvj1p 和 Vac8p 一起形成 Velcro 状斑块，通过该斑块，细胞核的泪滴状部分被夹入液泡腔，并通过称为细胞核零碎微自噬 (PMN) 的过程降解。 Osh1p 通过与 Nvj1p 的物理关联，靶向与 NVJ1 表达成比例的 NV 连接。该靶向不需要 NV 连接本身，因为在没有 Vac8p 的情况下，Osh1p 与 Nvj1p 共定位。 NV 连接相关的 Osh1p 也是 PMN 降解的底物。虽然 NV 连接形成或 PMN 不需要 OSH1，但 PMN 在缺乏酵母 OSBP 家族（Osh1p 至 Osh7p）的细胞中存在缺陷。相比之下，通过巨自噬将氨肽酶 I 靶向液泡的囊泡并不依赖于 Osh 蛋白家族。我们得出结论，核 PMN 囊泡的形成需要 Osh1p 和其他 Osh 家族成员的重叠活动。
OSH1 belongs to a seven-member gene family in yeast that is related to mammalian oxysterol-binding protein (OSBP). Here, we investigate the targeting of Osh1p to nucleus-vacuole (NV) junctions in Saccharomyces cerevisiae. NV junctions are interorganelle interfaces mediated by Nvj1p in the nuclear envelope and Vac8p on the vacuole membrane. Together, Nvj1p and Vac8p form Velcro-like patches through which teardrop-like portions of the nucleus are pinched off into the vacuolar lumen and degraded by a process termed piecemeal microautophagy of the nucleus (PMN). Osh1p is targeted to NV junctions proportional to NVJ1 expression through a physical association with Nvj1p. NV junctions per se are not required for this targeting because Osh1p colocalizes with Nvj1p in the absence of Vac8p. NV-junction-associated Osh1p is also a substrate for PMN degradation. Although OSH1 is not required for NV-junction formation or PMN, PMN is defective in cells lacking the yeast OSBP family (Osh1p to Osh7p). By contrast, the vesicular targeting of aminopeptidase I to the vacuole by macroautophagy is not dependent on the Osh protein family. We conclude the formation of nuclear PMN vesicles requires the overlapping activities of Osh1p and other Osh family members.