Kemble G W, Danieli T, White J M
Department of Pharmacology, University of California, San Francisco 94143-0450.
Cell. 1994 Jan 28;76(2):383-91. doi: 10.1016/0092-8674(94)90344-1.
It has been proposed that membrane fusion events such as virus-cell fusion proceed through a hemifusion intermediate, a state where lipids but not contents of the fusing compartments mix. We engineered the influenza hemagglutinin (HA) such that it would be anchored in membranes via a glycosylphosphatidylinositol (GPI) tail. GPI-anchored HA forms a trimer that can bind red blood cells (RBCs) and change conformation under fusion-inducing conditions. Using RBCs labeled with fluorescent lipid or fluorescent soluble content probes, we found that GPI-anchored HA mediated lipid mixing with similar time course and efficiency as wt-HA, yet did not mediate transfer of soluble contents. Hence, GPI-anchored HA appears to initiate, but not complete, a fusion reaction. We interpret our results as evidence for uncoupling a physiological fusion reaction, for trapping a hemifusion intermediate, and for assigning a role to a transmembrane domain in a fusion event.
有人提出，诸如病毒 - 细胞融合之类的膜融合事件是通过半融合中间体进行的，在这种状态下，融合隔室的脂质混合，但内容物不混合。我们对流感血凝素（HA）进行了改造，使其通过糖基磷脂酰肌醇（GPI）尾锚定在膜上。GPI锚定的HA形成三聚体，可结合红细胞（RBC）并在融合诱导条件下改变构象。使用标记有荧光脂质或荧光可溶性内容物探针的红细胞，我们发现GPI锚定的HA介导脂质混合的时间进程和效率与野生型HA相似，但不介导可溶性内容物的转移。因此，GPI锚定的HA似乎启动但未完成融合反应。我们将我们的结果解释为生理融合反应解偶联、捕获半融合中间体以及在融合事件中为跨膜结构域赋予作用的证据。
