Collins P L
Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892.
J Virol. 1990 Aug;64(8):4007-12. doi: 10.1128/JVI.64.8.4007-4012.1990.
cDNAs encoding the G glycoprotein of respiratory syncytial virus and the hemagglutinin-neuraminidase (HN) glycoprotein of parainfluenza virus type 3 were modified by site-specific mutagenesis and restriction fragment replacement to encode chimeric proteins consisting of the cytoplasmic and transmembrane domains of one protein fused to the ectodomain of the other. In the case of the HN ectodomain attached to the G transmembrane and cytoplasmic domains, cell surface expression of the chimera was reduced. Otherwise, the presence of the heterologous transmembrane and cytoplasmic domains had little effect on the processing of the HN or G ectodomain, as assayed by the acquisition of N-linked and O-linked carbohydrates, transport to the cell surface and, in the case of HN, folding, oligomerization, and hemadsorption activity. These results showed that the synthesis and processing of each ectodomain did not require the homologous transmembrane and cytoplasmic domains. In particular, O glycosylation of the G protein was specified fully by its ectodomain, even though this domain is highly divergent among the respiratory syncytial virus antigenic subgroups. In addition, whereas the cytoplasmic and transmembrane domains of the G protein were relatively highly conserved, they were nonetheless fully replaceable without significantly affecting processing.
通过定点诱变和限制性片段置换对编码呼吸道合胞病毒G糖蛋白和3型副流感病毒血凝素 - 神经氨酸酶（HN）糖蛋白的cDNA进行修饰，以编码嵌合蛋白，该嵌合蛋白由一种蛋白的胞质和跨膜结构域与另一种蛋白的胞外结构域融合而成。在HN胞外结构域连接到G跨膜和胞质结构域的情况下，嵌合体在细胞表面的表达降低。否则，通过获得N - 连接和O - 连接碳水化合物、转运到细胞表面以及（就HN而言）折叠、寡聚化和血细胞吸附活性测定，异源跨膜和胞质结构域的存在对HN或G胞外结构域的加工影响很小。这些结果表明，每个胞外结构域的合成和加工不需要同源的跨膜和胞质结构域。特别是，G蛋白的O糖基化完全由其胞外结构域决定，尽管该结构域在呼吸道合胞病毒抗原亚组中高度不同。此外，虽然G蛋白的胞质和跨膜结构域相对高度保守，但它们仍然可以完全替换而不会显著影响加工。
