Sec16 is a determinant of transitional ER organization
Sec16 is a determinant of transitional ER organization
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DOI：
10.1016/j.cub.2005.06.065
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发表时间：
2005-08-23
期刊：
影响因子：
9.2
通讯作者：
Glick, BS
中科院分区：
文献类型：
--
作者：
Connerly, PL;Esaki, M;Glick, BS
背景：蛋白质从内质网的过渡内质网 (tER) 位点输出，产生 COPII 囊泡。然而，人们对 COPII 成分如何集中在 tER 位点知之甚少。芽殖酵母毕赤酵母含有离散的 tER 位点，因此是研究 tER 组织的理想系统。结果：我们表明毕赤酵母中 tER 位点的完整性需要外周膜蛋白 Sec16。巴斯德毕赤酵母 Sec16 在 tER 位点的丰度比 COPII 外壳蛋白低一个数量级，并且似乎显示出与这些位点的饱和关联。 Sec16 中的温度敏感突变会导致 tER 在高温下断裂。这种效应是特定的，因为当 COPII 组装被 Sar1 GTPase 的显性失活形式抑制时，tER 位点保持完整。 sec16 突变体中的 tER 断裂伴随着高尔基体堆栈的破坏。结论：我们的数据表明 Secl 6 有助于将 COPII 外壳蛋白斑块组织成代表 tER 位点的簇。 sec16 突变体中发生的高尔基体破坏提供了芽殖酵母中高尔基体结构依赖于 tER 组织的证据。
Background: Proteins are exported from the ER at transitional ER (tER) sites, which produce COPII vesicles. However, little is known about how COPII components are concentrated at tER sites. The budding yeast Pichia pastoris contains discrete tER sites and is, therefore, an ideal system for studying tER organization. Results: We show that the integrity of tER sites in P. pastoris requires the peripheral membrane protein Sec16. P pastoris Sec16 is an order of magnitude less abundant than a COPII-coat protein at tER sites and seems to show a saturable association with these sites. A temperature-sensitive mutation in Sec16 causes tER fragmentation at elevated temperature. This effect is specific because when COPII assembly is inhibited with a dominant-negative form of the Sar1 GTPase, tER sites remain intact. The tER fragmentation in the sec16 mutant is accompanied by disruption of Golgi stacks. Conclusions: Our data suggest that Secl 6 helps to organize patches of COPII-coat proteins into clusters that represent tER sites. The Golgi disruption that occurs in the sec16 mutant provides evidence that Golgi structure in budding yeasts depends on tER organization.