MICROSTRUCTURAL HETEROGENEITY IN MEMBRANES

聚乙二醇（PEG）被广泛用于介导细胞间融合 在体细胞杂种的产生中以及在融合注射中， 将大分子从红细胞或脂质体导入培养细胞。 然而，关于PEG诱导细胞凋亡的机制知之甚少。 细胞膜的融合。 拟议的研究将继续 在分子细节上检查PEG对磷脂的影响， 囊泡作为更复杂生物膜中事件的模型。 初步阐明了PEG介导的细胞膜的作用机制 核聚变 所获得的信息将有助于推进PEG- 介导的细胞融合技术，以及提供线索， 体内细胞融合过程的分子机制， 内吞作用、胞吐排泄、蛋白质分选和转运，以及 病毒出芽和感染。 过去赠款期间的工作导致了一个假设的机制， PEG介导的融合：当发生融合时， 甘油中含有波动性脂质堆积缺陷的双层 通过脱水使主链区域进行分子接触 PEG的影响。 由此产生的融合概率是成比例的 临界双层间接近的概率和 内瓣叶或外瓣叶包装破裂的概率 双层的。 拟议的实验分为六个目标 它将检验并应用这一假设， 包括用病毒融合肽处理的复合膜 和培养的细胞膜：1]测试几种双层组分， 融合性的双层条件; 2]详细说明双层 与融合相关的结构特征; 3] 关键的双层结构，似乎与融合; 4] 使用几种光谱方法，测试是否存在 与PEG介导的双层包装相关的常见扰动 不同模型膜的融合; 5]检查如何一个非常小的 流感病毒N端“融合肽”的量 血凝素诱导低浓度凝集的膜融合， PEG浓度;和6]确定双层扰动物是否 在模型膜中作为融合剂的蛋白质 PEG介导的培养细胞融合。

Poly(ethylene glycol) (PEG) is used widely to mediate cell-cell fusion in the production of somatic cell hybrids and in the fusion injection of macromolecules into cultured cells from erythrocytes or liposomes. However, little is known about the mechanism by which PEG induces fusion of cell membranes. The proposed research will continue to examine in molecular detail the influence of PEG on phospholipid vesicles as a model for events in more complex biological membranes. The primary is to elucidate the mechanism of PEG-mediated membrane fusion. The information obtained will be useful for advancing PEG- mediated cell fusion technologies as well as for providing clues to the molecular mechanism of in vivo cell fusion processes such as endocytosis, exocytotic excretion, protein sorting and transport, and viral budding and infection. Work of the past grant period led to a hypothesis for the mechanism of PEG-mediated fusion: formation of fusion intermediates occurs when bilayers containing fluctuational lipid packing defects in the glycerol backbone region are brought into molecular contact by the dehydrating influence of PEG. The resulting probability of fusion is proportional to both the probability of critical inter-bilayer approach and to the probability of packing disruption in either the inner or outer leaflet of the bilayer. The proposed experiments are organized into six aims that will test and then apply this hypothesis to increasingly more complex membranes including ones treated with a viral fusion peptide and cultured cell membranes: 1] test several bilayer components and bilayer conditions for fusogenicity; 2] elaborate the bilayer structural characteristics associated with fusion; 3] test for a critical bilayer structure that seems to correlate with fusion; 4] using several spectroscopic approaches, test whether there exists a common perturbation in bilayer packing associated with PEG-mediated fusion of different model membranes; 5] examine how a very small quantity of the N-terminal "fusion peptide" of influenza virus hemagglutinin induces fusion of membranes aggregated by low concentrations of PEG; and 6] determine whether bilayer perturbants that act as fusogens in model membranes will increase the efficiency of PEG-mediated fusion of cultured cells.