McQueen N, Nayak D P, Stephens E B, Compans R W
Proc Natl Acad Sci U S A. 1986 Dec;83(24):9318-22. doi: 10.1073/pnas.83.24.9318.
In polarized epithelial cells, influenza virus buds exclusively from the apical domain of the plasma membrane, whereas vesicular stomatitis virus (VSV) buds exclusively from the basolateral domain. In virus-infected cells, the envelope proteins, influenza hemagglutinin (HA) and vesicular stomatitis virus G (VSV G), are likewise transported to and localized in the same domain of the plasma membrane from which the viruses bud. Previous studies have shown that influenza HA and VSV G proteins, when expressed from cloned cDNAs, are accumulated preferentially on the proper domains (apical and basolateral, respectively), indicating that the signal(s) for polarized transport resides in the polypeptide backbone of the proteins. To further elucidate the structural features required for apical vs. basolateral transport, we have constructed a gene that encodes a chimeric protein (H1GA) containing the external domain of HA and the transmembrane and cytoplasmic domains of VSV G. When the chimeric protein (H1GA) is expressed in CV1 cells using a simian virus 40 late expression vector, it is transported to the cell surface with kinetics similar to that of the native HA protein. Further, the chimeric protein, when expressed in polarized MDCK cells using a vaccinia virus early expression vector, is transported only to the apical surface, suggesting that the ectodomain of HA contains a signal for apical transport.
在极化上皮细胞中，流感病毒仅从质膜的顶端结构域出芽，而水疱性口炎病毒（VSV）仅从基底外侧结构域出芽。在病毒感染的细胞中，包膜蛋白，即流感血凝素（HA）和水疱性口炎病毒G蛋白（VSV G），同样被转运到病毒出芽的质膜同一结构域并定位于此。先前的研究表明，流感HA和VSV G蛋白从克隆的cDNA表达时，会优先积累在相应的结构域（分别为顶端和基底外侧），这表明极化转运的信号存在于蛋白质的多肽主链中。为了进一步阐明顶端与基底外侧转运所需的结构特征，我们构建了一个编码嵌合蛋白（H1GA）的基因，该嵌合蛋白包含HA的胞外结构域以及VSV G的跨膜和胞质结构域。当使用猴病毒40晚期表达载体在CV1细胞中表达嵌合蛋白（H1GA）时，它以与天然HA蛋白相似的动力学被转运到细胞表面。此外，当使用痘苗病毒早期表达载体在极化的MDCK细胞中表达该嵌合蛋白时，它仅被转运到顶端表面，这表明HA的胞外结构域包含顶端转运信号。
