TARGETING OF LYSOSOMAL ENZYMES

溶酶体存在于几乎所有的真核细胞中， 在生物降解中起作用的水解酶 物质. 溶酶体系统已经涉及到各种各样的 细胞功能;包括自溶、激素和药物调节 在炎症过程中作为组织破坏的介质。 溶酶体也参与了大量的人类遗传疾病 涉及一种或多种溶酶体酶的缺乏。 目前的研究 旨在了解细胞用于靶向的分子机制 溶酶体酶转化为溶酶体。 一个模型来解释这些目标 动物细胞中的酶最近被提出。 该模型指出， 特异性膜受体识别并结合翻译后 溶酶体酶特有的修饰。 这些受体移动到 酶被释放的地方。 然而，存在细胞系， 缺乏这些受体，因此必须以溶酶体酶为靶点， 不同的机制。 盘基网柄藻也缺乏这些受体 而且，由于它可以很容易地在基因和生化 操纵，代表了一个理想的有机体， 替代途径。 我们的研究涉及生物化学方法， 包括亚细胞分级分离和免疫细胞化学，以及 遗传方法，使用突变体在合成，修饰， 溶酶体酶的蛋白水解加工。 细胞发生了生化改变 基因方面将分析他们的能力， 定位溶酶体酶。 除了定义细胞内 途径后，溶酶体酶，这种方法将揭示 翻译后修饰和蛋白水解重要性 处理本地化事件。 最终，这些研究将 鉴定溶酶体上分选信号的分子性质 酶和参与定位过程的细胞成分， 缺乏磷酸甘露糖受体的细胞。

Lysosomes are found in virtually all eukaryotic cells and contain hydrolytic enzymes which function in the degradation of biological substances. The lysosomal system has been implicated in a wide variety of cellular functions; including autolysis, modulation of hormone and drug action and as mediators of tissue destruction during inflammation. Lysosomes are also involved in a large number of human genetic diseases involving a deficiency in one or more lysosomal enzyme. Current research is directed at understanding the molecular mechanisms cells use to target lysosomal enzymes to lysosomes. A model to explain the targeting of these enzymes in animal cells has recently been proposed. This model states that specific membrane receptors recognize and bind post-translational modifications unique to lysosomal enzymes. These receptors move to lysosomes where the enzymes are released. However, cell lines exist that lack these receptors and must therefore target lysosomal enzymes by a different mechanism. Dictyostelium discoideum also lack these receptors and, because of the ease in which it can be genetically and biochemically manipulated, represents an ideal organism in which to study this alternative pathway. Our research involves both a biochemical approach, consisting of subcellular fractionation and immunocytochemistry, and a genetic approach, using mutants altered in the synthesis, modification, and proteolytic processing of lysosomal enzymes. Cells altered biochemically and genetically will be analyzed with respect to their ability to properly localize lysosomal enzymes. In addition to defining the intracellular pathway followed by lysosomal enzymes, this approach will reveal the importance of both post-translational modification and proteolytic processing in the localization event. Ultimately, these studies will identify both the molecular nature of the sorting signal on lysosomal enzymes and the cellular components involved in the localization process in cells that lack phosphomannosyl receptors.