Wickham L, Duchaîne T, Luo M, Nabi I R, DesGroseillers L
Departments of Biochemistry, University of Montreal, Montreal, Quebec, Canada H3C 3J7.
Mol Cell Biol. 1999 Mar;19(3):2220-30. doi: 10.1128/MCB.19.3.2220.
Staufen (Stau) is a double-stranded RNA (dsRNA)-binding protein involved in mRNA transport and localization in Drosophila. To understand the molecular mechanisms of mRNA transport in mammals, we cloned human (hStau) and mouse (mStau) staufen cDNAs. In humans, four transcripts arise by differential splicing of the Stau gene and code for two proteins with different N-terminal extremities. In vitro, hStau and mStau bind dsRNA via each of two full-length dsRNA-binding domains and tubulin via a region similar to the microtubule-binding domain of MAP-1B, suggesting that Stau cross-links cytoskeletal and RNA components. Immunofluorescent double labeling of transfected mammalian cells revealed that Stau is localized to the rough endoplasmic reticulum (RER), implicating this RNA-binding protein in mRNA targeting to the RER, perhaps via a multistep process involving microtubules. These results are the first demonstration of the association of an RNA-binding protein in addition to ribosomal proteins, with the RER, implicating this class of proteins in the transport of RNA to its site of translation.
Staufen（Stau）是一种双链RNA（dsRNA）结合蛋白，参与果蝇中mRNA的运输和定位。为了了解哺乳动物中mRNA运输的分子机制，我们克隆了人类（hStau）和小鼠（mStau）的staufen cDNA。在人类中，Stau基因通过差异剪接产生四种转录本，编码两种具有不同N末端的蛋白质。在体外，hStau和mStau通过两个全长dsRNA结合结构域中的每一个结合dsRNA，并通过与MAP-1B的微管结合结构域相似的区域结合微管蛋白，这表明Stau交联细胞骨架和RNA成分。对转染的哺乳动物细胞进行免疫荧光双重标记显示，Stau定位于粗面内质网（RER），这表明这种RNA结合蛋白可能通过涉及微管的多步骤过程参与mRNA靶向RER。这些结果首次证明了除核糖体蛋白外，一种RNA结合蛋白与RER相关联，这表明这类蛋白参与RNA向其翻译位点的运输。
