Function of positive charges following signal-anchor sequences during translocation of the N-terminal domain
Function of positive charges following signal-anchor sequences during translocation of the N-terminal domain
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DOI：
10.1074/jbc.m506613200
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发表时间：
2006-01-13
影响因子：
4.8
通讯作者：
Sakaguchi, M
中科院分区：
文献类型：
--
作者：
Kida, Y;Morimoto, F;Sakaguchi, M
在内质网上膜蛋白的拓扑发生中，疏水性跨膜（TM）片段的方向受到侧翼氨基酸残基电荷的影响。我们评估了使用synaptotagmin II的疏水段下游的正电荷的功能。正电荷被不带电的残基系统地取代。虽然原始的TM片段易位的N末端，拓扑结构是颠倒的，这取决于突变。在突变体中，6个赖氨酸被转移到下游的方向受到影响，即使当6个赖氨酸是25个残基的疏水段。Lys在功能上被Arg取代，但不被Asp或Glu取代。多肽延伸过程中的作用时间表明，赖氨酸在核糖体出口位点的功能。我们认为，TM段的承诺，以一个特定的方向是由多肽链的远下游部分的影响，并退出核糖体后的正电荷被解码。
In topogenesis of membrane proteins on the endoplasmic reticulum, the orientation of the hydrophobic transmembrane (TM) segment is influenced by the charge of the flanking amino acid residues. We assessed the function of the positive charges downstream of the hydrophobic segment using synaptotagmin II. The positive charges were systematically replaced with non-charged residues. Although the original TM segment translocated the N terminus, the topology was inverted, depending on the mutations. Orientation was affected in mutants in which 6 Lys were shifted downstream, even when the 6 Lys were 25 residues from the hydrophobic segment. The Lys was functionally replaced by Arg, but not by Asp or Glu. The timing of action during polypeptide elongation indicated that the Lys functions at the ribosome exit sites. We suggest that the commitment of the TM segment to a particular orientation is influenced by far downstream parts of the polypeptide chain and that the positive charges are decoded after exiting the ribosome.