IMPORT OF HONEYBEE PREPROMELITTIN INTO THE ENDOPLASMIC-RETICULUM - STRUCTURAL BASIS FOR INDEPENDENCE OF SRP AND DOCKING PROTEIN
IMPORT OF HONEYBEE PREPROMELITTIN INTO THE ENDOPLASMIC-RETICULUM - STRUCTURAL BASIS FOR INDEPENDENCE OF SRP AND DOCKING PROTEIN
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DOI：
10.1002/j.1460-2075.1987.tb02476.x
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发表时间：
1987-07-01
期刊：
影响因子：
11.4
通讯作者：
ZIMMERMANN, R
中科院分区：
文献类型：
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作者：
MULLER, G;ZIMMERMANN, R
犬胰腺微粒体正确加工并导入蜜蜂前蜂毒素。通过信号序列去除检测，前promelittin插入微粒体膜不依赖于信号识别颗粒（SRP）和对接蛋白。我们解决了关于前熔融蛋白如何绕过SRP/对接蛋白系统的问题。构建了小鼠细胞质蛋白二氢叶酸还原酶与前体melittin或羧基末端截断衍生物之间的杂交蛋白。对这些杂交蛋白进行了膜插入和微粒体隔离分析。结果表明：(1)前驱melittin的信号序列能够与SRP/对接蛋白系统相互作用，但这种相互作用不是插入膜所必需的；这与卵磷脂前驱体的体积小有关。（ii）在前melittin中，一组带负电的氨基酸必须与一组带正电的氨基酸相平衡，以允许膜插入。（iii）一般来说，在短前体蛋白的情况下，一个信号序列足以独立于SRP和对接蛋白介导膜插入；然而，在这些前体的成熟部分，带电氨基酸的存在和分布可以发挥不同的作用。
Honeybee prepromelittin is correctly processed and imported by dog pancreas microsomes. Insertion of prepromelittin into microsomal membranes, as assayed by signal sequence removal, does not depend on signal recognition particle (SRP) and docking protein. We addressed the question as to how prepromelittin bypasses the SRP/docking protein system. Hybrid proteins between prepromelittin, or carboxy‐terminally truncated derivatives, and the cytoplasmic protein dihydrofolate reductase from mouse were constructed. These hybrid proteins were analysed for membrane insertion and sequestration into microsomes. The results suggest the following: (i) The signal sequence of prepromelittin is capable of interacting with the SRP/docking protein system, but this interaction is not mandatory for membrane insertion; this is related to the small size of prepromelittin. (ii) In prepromelittin a cluster of negatively charged amino acids must be balanced by a cluster of positively charged amino acids in order to allow membrane insertion. (iii) In general, a signal sequence can be sufficient to mediate membrane insertion independently of SRP and docking protein in the case of short precursor proteins; however, the presence and distribution of charged amino acids within the mature part of these precursors can play distinct roles.