STRUCTURE, BIOSYNTHESIS AND FUNCTION OF GLYCOPROTEINS

我们的研究有两个基础研究。第一个是要理解 糖蛋白的寡糖单元的合成以及它们是如何 在生物过程中起识别标记的作用。第二个是 从分子水平上理解新合成的溶酶体酶 被定向到溶酶体。对于第一个目标，我们计划使用凝集素- 寡糖生物合成中具有特异性阻断的抗性细胞系 发现低聚糖合成的新途径。几个 我们将探讨如何理解溶酶体酶的靶向性。第一, 我们计划确定溶酶体的共同蛋白质识别标记 生成磷酸甘露醇残留物所需的酶 作为识别信号，将蛋白质靶向溶酶体。至 做到这一点，我们将在分泌物之间构建嵌合分子 蛋白胃蛋白酶原和溶酶体酶组织蛋白酶D来定义 组织蛋白D上需要磷酸转移酶识别的区域 随后的磷酸化。我们计划克隆磷酸转移酶并 用此克隆研究粘脂病II和II患者的缺陷 三、两种常染色体隐性遗传疾病的磷酸转移酶。我们 还计划克隆α-N-乙酰氨基葡萄糖-1-磷酸二酯N- 乙酰氨基葡萄糖苷酶，是产生 草甘膦残留物。此外，我们计划对cDNAs进行突变 对于阳离子非依赖型和阳离子依赖型甘露糖6-磷酸 产生带有突变和缺失的受体分子的受体 它们的细胞质结构域。这些cDNAs将被导入受体 阴性小鼠L细胞测定对受体功能的影响 溶酶体酶在高尔基体分选，细胞表面有内吞作用。

Our studies have two basic studies. The first is to understand how the oligosaccharide units of glycoproteins are synthesized and how they function as recognition markers in biologic processes. The second is to understand at the molecular level how newly synthesized lysosomal enzymes are directed to lysosomes. For the first goal, we plan to use lectin- resistant cell lines with specific blocks in oligosaccharide biosynthesis to uncover new pathways for the synthesis of oligosaccharides. Several approaches will be made to understand lysosomal enzyme targeting. First, we plan to identify the common protein recognition marker for lysosomal enzymes required for the generation of phosphomannosyl residues which serve as the recognition signal for targeting proteins to lysosomes. To do this, we will construct chimeric molecules between the secretory protein pepsinogen and the lysosomal enzyme cathepsin D to define the regions on cathepsin D needed for recognition by phosphotransferase and subsequence phosphorylation. We plan to clone phosphotransferase and to use this clone to study the defects in patients with mucolipidosis II and III, two autosomal recessive genetic disorders of phosphotransferase. We also plan to clone alpha N-acetylglucosamine-1-phosphodiester N- acetylglucosaminidase, the second enzyme required for the generation of phosphomannosyl residues. In addition, we plan to mutagenize the cDNA's for the cation-independent and the cation-dependent mannose 6-phosphate receptors to generate receptor molecules with mutations and deletions in their cytoplasmic domains. These cDNA's will be transfected into receptor negative mouse L cells to determine the effects on receptor function in lysosomal enzyme sorting at the Golgi and endocytosis at the cell surface.