THE SACCHAROMYCES-CEREVISIAE SDC25 C-DOMAIN GENE-PRODUCT OVERCOMES THE DOMINANT INHIBITORY ACTIVITY OF HA-RAS ASN-17
THE SACCHAROMYCES-CEREVISIAE SDC25 C-DOMAIN GENE-PRODUCT OVERCOMES THE DOMINANT INHIBITORY ACTIVITY OF HA-RAS ASN-17
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DOI：
10.1128/mcb.13.1.39
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发表时间：
1993-01-01
影响因子：
5.3
通讯作者：
TOCOUE, B
中科院分区：
文献类型：
--
作者：
SCHWEIGHOFFER, F;CAI, H;TOCOUE, B
酿酒酵母 SDC25 基因产物的羧基末端部分（SDC25 C 结构域）可以引发哺乳动物 Ras 蛋白的激活。具体而言，SDC25 C 结构域在 CHO 细胞中充当细胞 Ras 蛋白的交换因子。在本研究中，我们使用显性抑制性 Ha-Ras Asn-17 突变体和 SDC25 C 结构域来进一步研究细胞 Ras 蛋白与其假定的内源鸟嘌呤核苷酸释放因子之间的相互作用。 NIH 3T3 细胞中 Ha-Ras Asn-17 的表达强烈抑制多瘤病毒胸苷激酶基因 (Py tk) 启动子的转录。 SDC25 C 结构域的共表达克服了 Ras 突变体对 Py tk 启动子的负面影响。另一方面，当 Ha-Ras Asn-17 的共表达量增加时，SDC25 C 结构域诱导的 Py tk 启动子 Ras 响应元件的反式激活消失。此外，SDC25 C结构域的共表达克服了Ha-Ras Asn-17对NIH 3T3细胞增殖的抑制。这些结果与 Ha-Ras Asn-17 突变体通过滴定细胞 Ras 蛋白上游激活剂发挥作用的观点一致。
The carboxy-terminal part of the Saccharomyces cerevisiae SDC25 gene product (SDC25 C domain) can elicit activation of mammalian Ras proteins. Specifically, SDC25 C domain functions as an exchange factor for cellular Ras proteins in CHO cells. In this study, we used the dominant inhibitory Ha-Ras Asn-17 mutant and SDC25 C domain to further investigate the interaction between cellular Ras proteins and their putative endogenous guanine nucleotide-releasing factors. Transcription from the polyomavirus thymidine kinase gene (Py tk) promoter is strongly inhibited by the expression of Ha-Ras Asn-17 in NIH 3T3 cells. Coexpression of SDC25 C domain overcomes the negative effect of the Ras mutant on the Py tk promoter. On the other hand, transactivation of the Ras-responsive element of the Py tk promoter induced by SDC25 C domain is lost upon coexpression of increasing amounts of Ha-Ras Asn-17. In addition, coexpression of SDC25 C domain overcomes the inhibition of proliferation of NIH 3T3 cells caused by Ha-Ras Asn-17. These results are consistent with the idea that the Ha-Ras Asn-17 mutant functions by titrating an upstream activator of cellular Ras proteins.