Pittet Martine, Conzelmann Andreas
Department of Medicine, Division of Biochemistry, Chemin du Musée 5, CH-1700 Fribourg, Switzerland.
Biochim Biophys Acta. 2007 Mar;1771(3):405-20. doi: 10.1016/j.bbalip.2006.05.015. Epub 2006 Jun 3.
Like most other eukaryotes, Saccharomyces cerevisiae harbors a GPI anchoring machinery and uses it to attach proteins to membranes. While a few GPI proteins reside permanently at the plasma membrane, a majority of them gets further processed and is integrated into the cell wall by a covalent attachment to cell wall glucans. The GPI biosynthetic pathway is necessary for growth and survival of yeast cells. The GPI lipids are synthesized in the ER and added onto proteins by a pathway comprising 12 steps, carried out by 23 gene products, 19 of which are essential. Some of the estimated 60 GPI proteins predicted from the genome sequence serve enzymatic functions required for the biosynthesis and the continuous shape adaptations of the cell wall, others seem to be structural elements of the cell wall and yet others mediate cell adhesion. Because of its genetic tractability S. cerevisiae is an attractive model organism not only for studying GPI biosynthesis in general, but equally for investigating the intracellular transport of GPI proteins and the peculiar role of GPI anchoring in the elaboration of fungal cell walls.
与大多数其他真核生物一样，酿酒酵母拥有一种糖基磷脂酰肌醇（GPI）锚定机制，并利用它将蛋白质附着于细胞膜。虽然少数GPI蛋白永久存在于质膜上，但它们中的大多数会进一步加工，并通过与细胞壁葡聚糖共价连接而整合到细胞壁中。GPI生物合成途径对于酵母细胞的生长和存活是必需的。GPI脂质在糙面内质网中合成，并通过一个由23种基因产物参与的包含12个步骤的途径添加到蛋白质上，其中19种是必需的。从基因组序列预测的大约60种GPI蛋白中，一些具有细胞壁生物合成和持续形态适应所需的酶促功能，其他一些似乎是细胞壁的结构成分，还有一些介导细胞黏附。由于其遗传易处理性，酿酒酵母不仅是研究一般GPI生物合成的有吸引力的模式生物，同样也是研究GPI蛋白的细胞内运输以及GPI锚定在真菌细胞壁形成中的特殊作用的理想选择。
