Boulay F, Doms R W, Webster R G, Helenius A
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510.
J Cell Biol. 1988 Mar;106(3):629-39. doi: 10.1083/jcb.106.3.629.
The influenza virus hemagglutinin (HA) is a well-characterized integral membrane glycoprotein composed of three identical subunits. We have analyzed the formation of mixed trimers in cells expressing two different HA gene products. The results show efficient and essentially random assembly of functional hybrid trimers provided that the HAs are from the same HA subtype. Trimerization is thus a posttranslational event, and subunits are recruited randomly from a common pool of monomers in the endoplasmic reticulum. Mixed trimers were not observed between HAs derived from different subtypes, indicating that the trimerization event is sequence specific. Mixed trimers containing mutant subunits were, moreover, used to establish that the acid-induced conformational change involved in the membrane fusion activity of HA is a highly cooperative event.
流感病毒血凝素（HA）是一种特征明确的整合膜糖蛋白，由三个相同的亚基组成。我们分析了表达两种不同HA基因产物的细胞中混合三聚体的形成情况。结果表明，只要HA来自同一HA亚型，功能性杂合三聚体就能高效且基本随机地组装。因此，三聚化是一个翻译后事件，亚基从内质网中共同的单体池中随机募集。在源自不同亚型的HA之间未观察到混合三聚体，这表明三聚化事件具有序列特异性。此外，含有突变亚基的混合三聚体被用于证实，HA膜融合活性中涉及的酸诱导构象变化是一个高度协同的事件。
