Protein targeting and integration signal for the chloroplastic outer envelope membrane
Protein targeting and integration signal for the chloroplastic outer envelope membrane
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DOI：
10.1105/tpc.8.11.2117
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发表时间：
1996-11-01
期刊：
影响因子：
11.6
通讯作者：
Chen, LJ
中科院分区：
文献类型：
--
作者：
Li, HM;Chen, LJ
叶绿体中的大多数蛋白质由核基因组编码并在细胞质中合成。除了大多数外被膜蛋白外，核编码的叶绿体蛋白是用含有这些蛋白的叶绿体靶向信息的N-末端延伸合成的。然而，大多数外膜蛋白在胞质溶胶中合成而不延伸。因此，不清楚叶绿体外膜靶向信息在这些多肽中的位置。我们分析了叶绿体外膜蛋白OEP 14（outer envelope membrane protein of 14 kD，以前命名为OM 14），将其外膜定位和整合信号定位于该蛋白的前30个氨基酸。该信号由带正电荷的N-末端部分和随后的疏水核心组成，与靶向内质网的蛋白质的信号肽相似。然而，嵌合蛋白含有这个信号融合到乘客蛋白没有整合到内质网膜。此外，膜拓扑结构分析表明，信号插入叶绿体外膜的方向相反的“积极的内部”规则预测。
Most proteins in chloroplasts are encoded by the nuclear genome and synthesized in the cytosol. With the exception of most outer envelope membrane proteins, nuclear-encoded chloroplastic proteins are synthesized with N-terminal extensions that contain the chloroplast targeting information of these proteins. Most outer membrane proteins, however, are synthesized without extensions in the cytosol. Therefore, it is not clear where the chloroplastic outer membrane targeting information resides within these polypeptides. We have analyzed a chloroplastic outer membrane protein, OEP14 (outer envelope membrane protein of 14 kD, previously named OM14), end localized its outer membrane targeting and integration signal to the first 30 amino acids of the protein. This signal consists of a positively charged N-terminal portion followed by a hydrophobic core, bearing resemblance to the signal peptides of proteins targeted to the endoplasmic reticulum. However, a chimeric protein containing this signal fused to a passenger protein did not integrate into the endoplasmic reticulum membrane. Furthermore, membrane topology analysis indicated that the signal inserts into the chloroplastic outer membrane in an orientation opposite to that predicted by the ''positive inside'' rule.