CHROMAFFIN GRANULE MEMBRANE

对分泌囊泡膜分选的研究已经 主要是由于缺乏关于分泌物的信息， 膜蛋白本身和缺乏任何 对应的cDNA。 这一建议解决了这两个问题。 肾上腺髓质嗜铬细胞与肾上腺髓质嗜铬细胞 交感神经元的特性;在刺激时， 通过分泌囊泡膜与血浆融合来响应 膜，从而释放其储存的内容物。 的 然后有效地再提取囊泡膜， 显然是被重新循环用于另一轮分泌。 在这种膜中发现了40到60种蛋白质; 这些都与任何已知的功能相关， 结构信息稀疏。 鉴于这个相对较小的 在颗粒膜中发现的蛋白质数量和 在生物化学上，颗粒占据着独特的Vantage， 神经模型系统，很明显，一个系统的结构 颗粒膜蛋白的分子生物学研究 基因分析将极大地有助于了解 生物学上重要的刺激分泌过程， 胞吐作用、囊泡膜融合、膜运输和 生物分子摄取 我们已经开始对这些基因进行分子遗传学鉴定 通过克隆编码膜蛋白的基因的一部分， 其中的一个子集;我们目前正在参与识别 克隆，随后确定克隆的 核苷酸序列，以及所编码氨基酸的推断 结构. 蛋白质结构的可测试预测 将使细胞膜和细胞内的 每一个的位置将通过免疫电子 显微镜 因此，这项工作将立即产生新的 这些蛋白质的结构信息。 我们还将拥有 它们的同源cDNA，允许分子遗传学研究 细胞膜的生物合成 未来的目标是检查 分子水平上的分泌膜分选将成为 可行 所获得的信息应主要适用于 整个交感肾上腺系统

Investigation of secretory vesicle membrane sorting has been hindered principally due to a lack of information on the secretory membrane proteins themselves and the absence of any corresponding cDNAs. This proposal addresses both problems. The adrenal medullary chromaffin cell shares many of the characteristics of the sympathetic neuron; upon stimulation, both respond by fusing secretory vesicle membrane with the plasma membrane with consequent release of their stored contents. The vesicular membrane is then efficiently re-extracted and apparently re-cycled to serve in another round of secretion. Between 40 and 60 proteins are found in this membrane; few of these have been correlated with any known function and structural information is sparse. Given this relatively small number of proteins found in the granule membrane and the biochemically unique vantage that the granule occupies as a neural model system, it is clear that a systematic structural investigation of the granule membrane proteins by molecular genetic analysis will be of enormous benefit in understanding the biologically important processes of stimulus-secretion and exocytosis, vesicular membrane fusion, membrane trafficking, and bio-molecule uptake. We have begun a molecular genetic characterization of these membrane proteins by cloning portions of the genes encoding a subset of them; we are currently involved in identification of the clones, to be followed by the determination of the cloned nucleotide sequences, and inferrence of the encoded amino acid structures. Testable predictions of the protein structure with respect to the membrane will be made and the intracellular location of each will be determined by immunoelectron microscopy. This work will therefore immediately result in new structural information about these proteins. We will also possess their cognate cDNAs, permitting molecular genetic investigations of the membrane's biogenesis. The future goal of examining secretory membrane sorting at the molecular level will become feasible. The information obtained should largely apply to the entire sympatho-adrenal system.