The N-terminal amphipathic alpha-helix of viperin mediates localization to the cytosolic face of the endoplasmic reticulum and inhibits protein secretion.
The N-terminal amphipathic alpha-helix of viperin mediates localization to the cytosolic face of the endoplasmic reticulum and inhibits protein secretion.
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DOI：
10.1074/jbc.m807261200
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发表时间：
2009-02-13
期刊：
影响因子：
--
通讯作者：
Cresswell P
中科院分区：
文献类型：
--
作者：
Hinson ER;Cresswell P
蝰蛇蛋白是一种进化上保守的干扰素诱导蛋白，定位于内质网（ER）并抑制许多DNA和RNA病毒。在这项研究中，我们报告，蝰蛇蛋白特异性地定位于ER的细胞质面，并且其N末端的两亲性α-螺旋对于蝰蛇蛋白的ER定位是必需的，并且足以促进报告蛋白dsRed的ER定位。过表达完整的蝰蛇蛋白而不是融合到dsRed的两亲性α-螺旋诱导晶体状ER。与其他诱导晶体状ER的蛋白质一致，蝰蛇蛋白自我缔合，并且它独立于两亲性α-螺旋。蝰蛇蛋白的表达也影响了可溶性的，但不是膜相关蛋白的运输。完整的蝰蛇蛋白或N-末端α-helix-dsRed融合蛋白的表达显著降低可溶性碱性磷酸酶的分泌，并降低其ER向高尔基体运输的速率。同样，viperin表达抑制HepG 2细胞的大量蛋白分泌和内源性α1-抗胰蛋白酶和血清白蛋白的分泌。将N-末端α-螺旋中的疏水残基转化为酸性残基部分或完全恢复了可溶性碱性磷酸酶的正常转运，这表明N-末端α-螺旋结构域的延伸的两亲性对于抑制蛋白质分泌是必需的。
Viperin is an evolutionarily conserved interferon-inducible protein that localizes to the endoplasmic reticulum (ER) and inhibits a number of DNA and RNA viruses. In this study, we report that viperin specifically localizes to the cytoplasmic face of the ER and that an amphipathic α-helix at its N terminus is necessary for the ER localization of viperin and sufficient to promote ER localization of a reporter protein, dsRed. Overexpression of intact viperin but not the amphipathic α-helix fused to dsRed induced crystalloid ER. Consistent with other proteins that induce crystalloid ER, viperin self-associates, and it does so independently of the amphipathic α-helix. Viperin expression also affected the transport of soluble but not membrane-associated proteins. Expression of intact viperin or an N-terminal α-helix-dsRed fusion protein significantly reduced secretion of soluble alkaline phosphatase and reduced its rate of ER-to-Golgi trafficking. Similarly, viperin expression inhibited bulk protein secretion and secretion of endogenous α1-antitrypsin and serum albumin from HepG2 cells. Converting hydrophobic residues in the N-terminal α-helix to acidic residues partially or completely restored normal transport of soluble alkaline phosphatase, suggesting that the extended amphipathic nature of the N-terminal α-helical domain is essential for inhibiting protein secretion.