Influenza B Virus BM2 Protein Is Transported through the trans-Golgi Network as an Integral Membrane Protein
Influenza B Virus BM2 Protein Is Transported through the trans-Golgi Network as an Integral Membrane Protein
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DOI：
10.1128/jvi.77.19.10630-10637.2003
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发表时间：
2003-10
影响因子：
5.4
通讯作者：
Shinji Watanabe;M. Imai;Y. Ohara;T. Odagiri
中科院分区：
文献类型：
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作者：
Shinji Watanabe;M. Imai;Y. Ohara;T. Odagiri
摘要从B型流感病毒RNA片段7转录而来的A双顺反子基因编码两种病毒蛋白，即基质蛋白M1和未鉴定的小蛋白BM2。在本研究中，我们重点研究了BM2的细胞质转运和细胞膜结合。病毒感染细胞的免疫荧光研究表明，BM2在合成后立即聚集在高尔基体，然后通过反式高尔基体网络运输到质膜。对一组BM2缺失突变体的定位表明，BM2的N端一半(残基2至50)对其运输至关重要，特别是残基2至23的缺失导致蛋白质在整个细胞中扩散分布。蔗糖梯度浮选和膜生化分析表明，BM2作为一种完整的膜蛋白与细胞膜紧密结合。通过差异表位标记的BM2蛋白的共沉淀，证实了BM2的寡聚化。综上所述，这些结果有力地表明，BM2除了血凝素、神经氨酸酶和Nb外，还以第四膜蛋白的形式整合到质膜的N端疏水结构域中。
ABSTRACT A bicistronic mRNA transcribed from the influenza B virus RNA segment 7 encodes two viral proteins, matrix protein M1 and uncharacterized small protein BM2. In the present study, we focused on the cytoplasmic transport and cellular membrane association of BM2. Immunofluorescence studies of virus-infected cells indicated that BM2 accumulated at the Golgi apparatus immediately after synthesis and then was transported to the plasma membrane through the trans-Golgi network. Localization of a set of BM2 deletion mutants revealed that the N-terminal half of BM2 (residues 2 to 50) was crucial for its transport; in particular, the deletion of residues 2 to 23, deduced to be a transmembrane domain, resulted in diffused distribution of the protein throughout the entire cell. Sucrose gradient flotation and biochemical analyses of the membrane showed that BM2 was tightly associated with cellular membranes as an integral membrane protein. Oligomerization of BM2 was demonstrated by coprecipitation of differentially epitope-tagged BM2 proteins. Taken together, these results strongly suggest that BM2 is integrated into the plasma membrane at the N-terminal hydrophobic domain as fourth membrane protein, in addition to hemagglutinin, neuraminidase, and NB, of the influenza B virus.