RNA开关或核糖开关（涉及小配体向RNA上的结合）已知在细菌、真菌和植物中调控基因表达，在那里它们对各种不同的代谢物或营养物的缺乏或过多频繁做出反应。
现在，一种RNA开关已在人类细胞中被发现。它是编码“血管内皮细胞生长因子”（VEGF）的mRNA的3′未转译区域的一个成分，而VEGF则是对血管形成非常关键的一种蛋白。可开关的mRNA可结合两种不同的复合物：GAIT 或 hnRNP L。其中一种的结合诱导产生一个特定的构形，它会阻止另一种的结合。具体结合哪个因子，取决于指示炎症和缺氧状态的环境信号。该开关的形成可能是为了维持对缺氧或发炎组织的氧供应，并且可能是在多细胞动物中调控基因表达的一种依赖于蛋白的RNA开关的例子（在这些动物体内，对不同输入信号的精确集成要比迅速反应更为重要）。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 457, 915-919 (12 February 2009) | doi:10.1038/nature07598
A stress-responsive RNA switch regulates VEGFA expression
Partho Sarothi Ray1,2, Jie Jia1, Peng Yao1, Mithu Majumder3, Maria Hatzoglou3 & Paul L. Fox1
1 Department of Cell Biology, The Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, Ohio 44195, USA
2 Department of Biology, Indian Institute of Science Education and Research, Kolkata 700106, India
3 Department of Nutrition, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA
Ligand binding to structural elements in the non-coding regions of messenger RNA modulates gene expression1, 2. Ligands such as free metabolites or other small molecules directly bind and induce conformational changes in regulatory RNA elements known as riboswitches1, 2, 3, 4. Other types of RNA switches are activated by complexed metabolites—for example, RNA-ligated metabolites such as aminoacyl-charged transfer RNA in the T-box system5, or protein-bound metabolites in the glucose- or amino-acid-stimulated terminator-anti-terminator systems6, 7. All of these switch types are found in bacteria, fungi and plants8, 9, 10. Here we report an RNA switch in human vascular endothelial growth factor-A (VEGFA, also known as VEGF) mRNA 3' untranslated region (UTR) that integrates signals from interferon (IFN)-and hypoxia to regulate VEGFA translation in myeloid cells. Analogous to riboswitches, the VEGFA 3' UTR undergoes a binary conformational change in response to environmental signals. However, the VEGFA 3' UTR switch is metabolite-independent, and the conformational change is dictated by mutually exclusive, stimulus-dependent binding of proteins, namely, the IFN--activated inhibitor of translation complex11, 12 and heterogeneous nuclear ribonucleoprotein L (HNRNPL, also known as hnRNP L). We speculate that the VEGFA switch represents the founding member of a family of signal-mediated, protein-dependent RNA switches that evolved to regulate gene expression in multicellular animals in which the precise integration of disparate inputs may be more important than the rapidity of response.
