Oh D, Hopper J E
Department of Biological Chemistry, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Mol Cell Biol. 1990 Apr;10(4):1415-22. doi: 10.1128/mcb.10.4.1415-1422.1990.
The Saccharomyces cerevisiae GAL5 (PGM2) gene was isolated and shown to encode the major isozyme of phosphoglucomutase. Northern (RNA) blot hybridization revealed that the GAL5 transcript level increased three- to fourfold in response to galactose and was severely repressed in response to glucose. Total cellular phosphoglucomutase activity was likewise responsive to galactose and to glucose, and this responsiveness was found to be due primarily to variation in the activity of the major isozyme of phosphoglucomutase. These results imply that the major and minor isozymes of phosphoglucomutase have distinct roles in yeast cells. The galactose inducibility of GAL5 was found to be under the control of the GAL4, GAL80, and GAL3 genes. In striking contrast to other galactose-inducible genes, the GAL5 gene exhibited an unusually high GAL4-independent basal level of expression. These results have implications for metabolic trafficking.
酿酒酵母GAL5（PGM2）基因被分离出来，并被证明编码磷酸葡萄糖变位酶的主要同工酶。Northern（RNA）印迹杂交显示，GAL5转录本水平在半乳糖刺激下增加了三到四倍，而在葡萄糖刺激下则受到严重抑制。细胞总磷酸葡萄糖变位酶活性同样对半乳糖和葡萄糖有反应，并且发现这种反应主要是由于磷酸葡萄糖变位酶主要同工酶活性的变化。这些结果表明，磷酸葡萄糖变位酶的主要和次要同工酶在酵母细胞中具有不同的作用。发现GAL5的半乳糖诱导性受GAL4、GAL80和GAL3基因的控制。与其他半乳糖诱导基因形成鲜明对比的是，GAL5基因表现出异常高的不依赖GAL4的基础表达水平。这些结果对代谢运输具有重要意义。
