Structure and function of the ubiquitin ligase that recognizes N-linked oligosaccharides

识别N-连接寡糖的泛素连接酶的结构和功能

• 批准号: 14580635
• 负责人: TAI Tadashi
• 金额: $ 1.98万
• 依托单位: The Tokyo Metropolitan Organization of Medical Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14580635/
• 关键词: N-glycan; ubiquitin ligase; Fbx2; proteasome; ERAD; Neuron; ニューロン; インテグリン

N-glycosylation of proteins in the endoplasmic reticulum (ER) plays a key role in the protein quality control. Here we report that N-glycan serves as a degradation signal by the novel SCF^<Fbx2> ubiquitin-ligase complex in the cytosol. Fbx2,a F-box protein, binds specifically to proteins attached with N-linked high mannose type oligosaccharides, and subsequently contributes to ubiquitylation of N-glycosylated proteins. We identified pre-integrin β1 as one of the Fbx2 targets. This interaction was detected in the cytosol when the proteasome was inhibited. Furthermore, expression of Fbx2ΔF lacking the F-box domain essential for the formation of the SCF complex appreciably blocked degradation of typical substrates of ER-associated degradation, such as cystic fibrosis transmembrane conductance regulator mutant CFTRΔF508 and T-cell receptor a subunit, and Fbx2 suppressed aggregation of CFTRΔF508. These results indicate that SCF^<Fbx2> ubiquitylates N-glycosylated proteins, which are translocated from the ER to the cytosol by the quality control mechanism.

内质网中蛋白质的N-糖基化在蛋白质质量控制中起着关键作用。在这里，我们报告，N-聚糖作为一个降解信号的新SCF β-<Fbx2>泛素连接酶复合物在胞质溶胶中。Fbx 2是一种F-box蛋白，与N-连接的高甘露糖型寡糖连接的蛋白质特异性结合，随后有助于N-糖基化蛋白的泛素化。我们将前整合素β1鉴定为Fbx 2靶点之一。当蛋白酶体被抑制时，在胞质溶胶中检测到这种相互作用。此外，缺乏形成SCF复合物所必需的F-box结构域的Fbx 2 ΔF的表达可明显阻断ER相关降解的典型底物的降解，例如囊性纤维化跨膜传导调节因子突变体CFTRΔF508和T细胞受体a亚基，并且Fbx 2抑制CFTRΔF508的聚集。这些结果表明，SCF<Fbx2>-2使N-糖基化蛋白泛素化，所述N-糖基化蛋白通过质量控制机制从ER易位到胞质溶胶。

项目成果

Li, Y-T., et al.: "Association of GM4 ganglioside with membrane surrounding lipid droplets in shark liver."J. Lipid Res.. 43. 1019-1025 (2002)

Li, Y-T., et al.：“GM4 神经节苷脂与鲨鱼肝脏中脂滴周围膜的关联。”J.

Ogura, K.: "Molecular cloning and characterigation of GEF-1"Neurochemical Research. 27. 779-784 (2002)

Ogura, K.：“GEF-1 的分子克隆和表征”神经化学研究。

Yoshida, Y., et al.: "E3 ubiquitin ligase that recognizes sugar chains."Nature. 418. 438-442 (2002)

Yoshida, Y., et al.：“识别糖链的 E3 泛素连接酶。”《自然》。

Yoshida, Y.: "Fbs2 is a new member of the E3 ubiquitin ligase family."J.Biol.Chem.. 278. 43877-43884 (2003)

Yoshida, Y.：“Fbs2 是 E3 泛素连接酶家族的新成员。”J.Biol.Chem.. 278. 43877-43884 (2003)

Ogura, K., et al.: "Molecular cloning and characterization of Galactosylceramide Expression Factor-1 (GEF-1)."Neurochem.Res.. 27. 779-784 (2002)

Ogura, K. 等人：“半乳糖神经酰胺表达因子 1 (GEF-1) 的分子克隆和表征。”Neurochem.Res.. 27. 779-784 (2002)