Phosphatidylethanolamine binding protein 4 (PEBP4) is a secreted protein and has multiple functions.
Phosphatidylethanolamine binding protein 4 (PEBP4) is a secreted protein and has multiple functions.
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磷脂酰乙醇胺结合蛋白 4 (PEBP4) 是一种分泌蛋白，具有多种功能
DOI：
10.1016/j.bbamcr.2016.03.022
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发表时间：
2016-07
期刊：
影响因子：
--
通讯作者：
Luo Z
中科院分区：
文献类型：
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作者：
He H;Liu D;Lin H;Jiang S;Ying Y;Chun S;Deng H;Zaia J;Wen R;Luo Z
磷脂酰乙醇胺结合蛋白（PEBP）代表从细菌到人类保守的蛋白质超家族。在哺乳动物中，已经确定了四个成员，PEBP 1 -4。为了确定PEBP 1 -4之间的功能差异及其作用的潜在机制，我们进行了序列比对，发现PEBP 4含有信号肽和潜在的糖基化位点，而PEBP 1 -3是细胞内蛋白。为了测试PEBP 4是否被分泌，我们制备了在氨基（N）末端或羧基（C）末端具有Myc表位的构建体，以分别掩蔽信号序列或使其保持游离。我们的数据显示，当表位在其C-末端被标记时，小鼠和人PEBP 4都被分泌。令我们惊讶的是，分泌除了依赖于N-末端信号序列之外还依赖于C-末端保守结构域。当表位被置于N-末端时，重组蛋白不能分泌，而是保留在细胞质中。质谱法检测到分泌的PEBP 4上的天冬酰胺（N）-糖基化。尽管N-末端标记的PEBP 4的过表达导致EGF对ERK活化的抑制，但具有C-末端表位标记的EGF没有这种作用。同样，PEBP 4 shRNA的转染似乎不影响ERK激活，表明PEBP 4不参与该途径的调节。相比之下，PEBP 4 siRNA抑制Act在S473处的磷酸化。因此，我们的研究结果表明PEBP 4是一种多功能蛋白，可以分泌。研究PEBP 4分泌和调节细胞事件的机制将是重要的。
Phosphatidylethanolamine binding proteins (PEBP) represent a superfamily of proteins that are conserved from bacteria to humans. In mammals, four members have been identified, PEBP1–4. To determine the functional differences among PEBP1–4 and the underlying mechanism for their actions, we performed a sequence alignment and found that PEBP4 contains a signal peptide and potential glycosylation sites, whereas PEBP1–3 are intracellular proteins. To test if PEBP4 is secreted, we made constructs with Myc epitope at the amino (N) terminus or carboxyl (C) terminus to mask the signal sequence or keep it free, respectively. Our data revealed that both mouse and human PEBP4 were secreted when the epitope was tagged at their C-terminus. To our surprise, secretion was dependent upon the C-terminal conserved domain in addition to the N-terminal signal sequence. When the epitope was placed to the N-terminus, the recombinant protein failed to secrete and instead, was retained in the cytoplasm. Mass spectrometry detected asparagine (N)-glycosylation on the secreted PEBP4. Although overexpression of N-terminal tagged PEBP4 resulted in an inhibition of ERK activation by EGF that with a C-terminal epitope tag did not have such an effect. Likewise, transfection of PEBP4 shRNA did not appear to affect ERK activation, suggesting that PEBP4 does not participate in the regulation of this pathway. In contrast, PEBP4 siRNA suppressed phosphorylation of Act at S473. Therefore, our results suggest that PEBP4 is a multifunctional protein and can be secreted. It will be important to investigate the mechanism by which PEBP4 is secreted and regulates cellular events.