MOLECULAR STUDIES OF EUKARYOTIC CELL SURFACE GROWTH

真核细胞表面生长的分子研究

• 批准号: 3274174
• 负责人: RANDY W. SCHEKMAN
• 金额: $ 31.9万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 1979
• 资助国家: 美国
• 起止时间: 1979-07-01 至 1992-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3274174
• 关键词: Saccharomyces; acid phosphatase; beta fructofuranosidase; carbohydrate structure; electron microscopy; enzyme structure; eukaryote; fungal genetics; glycoproteins; immunochemistry; membrane reconstitution /synthesis; radiotracer; secretion; temperature sensitive mutant

We have isolated a series of yeast secretory mutants (sec mutants) that are temperature-sensitive for cell surface growth, division, and secretion. Most of these mutants accumulate secretory proteins in an intracellular pool which can be released when cells are returned to a permissive temperature. At least 23 gene products have been implicated in the process of delivering membrane and secretory proteins to the cell surface. Electron microscope analysis has revealed three distinct membrane-bounded organelles that accumulate in different mutants. Ten of the mutants produce vesicles, nine of the mutants produce endoplasmic reticulum, and two of the mutants produce Golgi body-like structures which we have called Berkely bodies. We have also identified nine genes that contrrl the earliest steps in the cell surface growth pathway. Mutations in these genes result in a failure to synthesize active secretory protein, in spite of a normal rate of overall protein synthesis. Two of the mutants are also defective in the production of a membrane permease activity. The secretory mutants are now being used to identify some of the molecular events involved in cell-surface growth. In higher eukaryotic cells, glycoproteins are glycosylated in stages during their transit to the cell surface and thus if a secretory mutant blocks passage from one stage to another, incompletely glycosylated forms may accumulate. We have detected at least two stages in oligosaccharide assembly on the secretory enzyme invertase. The secretory mutants that accumulate endoplasmic reticulum at a nonpermissive temperature produce an incompletely glycosylated form of invertase.

我们已经分离出一系列酵母分泌突变体(SEC突变体)，它们是 对细胞表面生长、分裂和分泌具有温度敏感性。大部分 这些突变体在细胞内池中积累分泌蛋白，这种池可以 当电池返回到允许的温度时，释放。至少23 基因产物已经被牵连到传递膜和 分泌蛋白质到细胞表面。电子显微镜分析有 发现了三个不同的膜结合细胞器，它们积累在不同的 变种人。10个突变株产生囊泡，9个突变株产生囊泡 内质网，其中两个突变体产生高尔基体样结构 我们称之为伯克利肉体。 我们还确定了九个控制细胞中最早步骤的基因 表面生长途径。这些基因的突变导致无法 合成活性分泌蛋白，尽管总体速度正常 蛋白质合成。其中两个突变体在生产一种 膜通透酶活性。 分泌型突变体现在被用来鉴定一些分子 参与细胞表面生长的事件。在高等真核细胞中， 糖蛋白在转运到细胞的过程中被分阶段糖基化。 因此，如果一个分泌突变体阻止了从一个阶段到另一个阶段的通道， 不完全糖基化的形式可能会累积。我们检测到至少两个 低聚糖在分泌酶转化酶上的组装阶段。这个 在不允许的情况下积累内质网的分泌型突变体 温度会产生一种不完全糖化形式的转化酶。