United States Department of Agriculture ⁄Agricultural Research Service Children’s Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA.
Plant Biol (Stuttg). 2010 Nov;12(6):935-9. doi: 10.1111/j.1438-8677.2010.00368.x.
The biochemical properties and regulation of several plant CAX (CAtion eXchanger)-type vacuolar Ca2+/H+ exchangers have been extensively analysed in yeast expression assays. In the present study, we compare and contrast the phenotypes of yeast cells expressing the CAX1 cDNA and open reading frame (ORF). We report that the CAX1 ORF, but not the cDNA containing the 3′-untranslated region (UTR), was able to confer Ca2+ tolerance when expressed in a Ca2+-sensitive yeast mutant. Additionally, only yeasts expressing the N-terminal truncated CAX1 ORF were able to grow on high Mn2+ media, suggesting that removal of the 3′-UTR altered activity. However, removal of the 3′-UTR from another CAX did not alter the yeast phenotypes. Expression studies demonstrated that expressing the CAX1 ORF in yeast elevates CAX1 RNA and protein levels. Our results suggest that the 3′-UTR modulates expression of CAX1 in yeast.
几种植物 CAX（Ca2+ 交换器）型液泡 Ca2+/H+ 交换器的生化特性和调控已在酵母表达试验中得到广泛分析。在本研究中，我们比较和对比了表达 CAX1 cDNA 和开放阅读框（ORF）的酵母细胞的表型。我们报告说，CAX1 ORF，但不是包含 3′-非翻译区（UTR）的 cDNA，在 Ca2+ 敏感的酵母突变体中表达时能够赋予 Ca2+ 耐受性。此外，只有表达 N 端截断 CAX1 ORF 的酵母才能在高 Mn2+ 培养基上生长，这表明 3′-UTR 的缺失改变了活性。然而，从另一种 CAX 中去除 3′-UTR 并没有改变酵母的表型。表达研究表明，在酵母中表达 CAX1 ORF 会提高 CAX1 RNA 和蛋白水平。我们的结果表明，3′-UTR 调节 CAX1 在酵母中的表达。
