CHARACTERIZATION OF A FISSION YEAST GENE, GPA2, THAT ENCODES A G-ALPHA-SUBUNIT INVOLVED IN THE MONITORING OF NUTRITION
CHARACTERIZATION OF A FISSION YEAST GENE, GPA2, THAT ENCODES A G-ALPHA-SUBUNIT INVOLVED IN THE MONITORING OF NUTRITION
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DOI：
10.1101/gad.6.12b.2455
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发表时间：
1992-12-01
影响因子：
10.5
通讯作者：
YAMAMOTO, M
中科院分区：
文献类型：
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作者：
ISSHIKI, T;MOCHIZUKI, N;YAMAMOTO, M
裂殖酵母gpa2基因是通过与盘基网柄菌Galpha1的cDNA杂交而克隆的。它编码具有354个氨基酸的G蛋白α亚基的同源物，预测分子量为40，522。gpa2的破坏减缓了细胞的生长，但并不致命。gpa2缺陷的细胞在充足的营养存在下很容易交配和形成孢子，绕过了启动性发育所需的氮饥饿。这些表型模仿那些在编码腺苷酸环化酶的BTA1中有缺陷的细胞。gpa2无效突变体中的cAMP水平仅为野生型水平的三分之一。gpa2中可能抑制基因产物的GT β活性的突变引起细胞内cAMP水平轻微增加并导致渗漏性不育。如果细胞携带这种类型的gpa2突变和编码磷酸二酯酶的pde1中的无效突变，则cAMP水平达到野生型水平的20倍。gpa2缺陷的细胞在葡萄糖刺激下产生cAMP。这些结果表明，Gpa2参与根据营养条件的cAMP水平的测定，最有可能作为腺苷酸环化酶的正调节剂。
The Schizosaccharomyces pombe gpa2 gene was cloned by hybridization with a cDNA for Dictyostelium discoideum Galpha1. It encodes a homolog of G-protein alpha-subunits with 354 amino acids and a predicted molecular mass of 40,522. Disruption of gpa2 slows cell growth but is not lethal. Cells defective in gpa2 mate and sporulate readily in the presence of plentiful nutrition, bypassing the requirement of nitrogen starvation for the initiation of sexual development. These phenotypes mimic those of cells defective in cyr1 encoding adenylyl cyclase. The level of cAMP in gpa2 null mutants is only one-third of the wild-type level. Mutations in gpa2 that are likely to inhibit the GTPase activity of the gene product cause a slight increase in intracellular cAMP levels and result in leaky sterility. The cAMP level reaches 20 times as high as the wild-type level if a cell carries both this type of gpa2 mutation and a null mutation in pde1 encoding phosphodiesterase. Cells defective in gpa2 fait to produce cAMP in response to glucose stimulation. These results suggest that Gpa2 is involved in the determination of the cAMP level according to nutritional conditions, most likely as a positive regulator of adenylyl cyclase.