CELL FUSION IN MODEL AND BIOLOGICAL MEMBRANE SYSTEMS

该提案的长期目标是阐明分子 膜融合机制参与胞吐过程，以 更好地理解和控制生物分泌现象 在正常和病理条件下。 为此，对两种模型的膜融合进行了平行研究， 膜和分泌系统中的生物膜。 在模型膜系统（脂质囊泡、单层膜和单层膜）中的膜融合 双层膜），温度 和渗透压梯度将被检查的情况下， 没有蛋白质或胆固醇掺入膜中。 的影响 各种融合物质，生物分子（即，花生四烯酸和 多胺）和磷酸钙对膜融合的影响。 膜融合将与自由能增加的程度相关 在膜表面由于离子的结合而脱水结合 水从膜表面的情况下，二价阳离子诱导 融合，由于膜膨胀的情况下的温度或渗透 压力梯度诱导膜融合，并且由于膜表面 可能由钙结合蛋白介导的构象变化。 为了将我们关于膜融合的知识应用于模型脂质， 膜系统到生物膜系统的相互作用与融合 在脂膜和生物膜（突触囊泡， 嗜铬颗粒、红细胞囊泡等）将沿着 与上面总结的路线相同。 用于这些实验的方法将包括荧光和 发光融合分析，光散射测量，动态光 散射技术，用微量天平的重量测量，NMR， 电子显微镜，相差显微镜观察，和其他 物理化学（表面化学等）技术来确定 膜及其组分的性质。

The long term goals of this proposal are to elucidate the molecular mechanism of membrane fusion involved in exocytotic processes, in order to have a better understanding and control of biological secretion phenomena under normal and pathological conditions. For this purpose, parallel studies of membrane fusion for both model membranes and biological membranes in secretory systems will be performed. Membrane fusion in model membrane systems (lipid vesicles, monolayer and bilayer membranes) induced by divalent (or polyvalent) cations, temperature and osmotic pressure gradients will be examined for the cases with and without proteins or cholesterol incorporated in the membranes. Effects of various fusogenic substances, biomolecules (i.e., arachidonic acid and polyamines) and calcium-phosphate on membrane fusion will also be studied. Membrane fusion will be correlated with the degree of free-energy increase in the membrane surface due to ion binding to and dehydration of bound water from the membrane surface for the case of divalent cation induced fusion, due to membrane expansion for the case of temperature or osmotic pressure gradient induced membrane fusion, and due to membrane surface conformational change possibly mediated by calcium binding proteins. In order to apply our knowledge about membrane fusion in model lipid membrane systems to biological membrane systems, the interaction and fusion between lipid membranes and biological membranes (synaptic vesicles, chromaffin granules, erythrocyte vesicles, etc.) will be examined along the same lines as summarized above. Methods to be used for these experiments will include fluorescence and luminescence fusion assays, light scattering measurements, dynamical light scattering techniques, weight measurements with a microbalance, NMR, electron microscopy, phase contrast microscopic observation, and other physico-chemical (surface chemistry, etc.) techniques to determine properties of the membranes and their constituents.