Craig A W, Haghighat A, Yu A T, Sonenberg N
Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
Nature. 1998 Apr 2;392(6675):520-3. doi: 10.1038/33198.
In the initiation of translation in eukaryotes, binding of the small ribosomal subunit to the messenger RNA results from recognition of the 5' cap structure (m7GpppX) of the mRNA by the cap-binding complex eIF4F. eIF4F is itself a three-subunit complex comprising the cap-binding protein eIF4E, eIF4A, an ATP-dependent RNA helicase, and eIF4G, which interacts with both eIF4A and eIF4E and enhances cap binding by eIF4E. The mRNA 3' polyadenylate tail and the associated poly(A)-binding protein (PABP) also regulate translational initiation, probably by interacting with the 5' end of the mRNA. In yeast and plants, PABP interacts with eIF4G but no such interaction has been reported in mammalian cells. Here, we describe a new human PABP-interacting protein, PAIP-I, whose sequence is similar to the central portion of eIF4G and which interacts with eIF4A. Overexpression of PAIP-1 in COS-7 cells stimulates translation, perhaps by providing a physical link between the mRNA termini.
在真核生物的翻译起始过程中，小核糖体亚基与信使RNA的结合是由于帽结合复合物eIF4F识别了mRNA的5'帽结构（m7GpppX）。eIF4F本身是一个三聚体复合物，由帽结合蛋白eIF4E、eIF4A（一种依赖ATP的RNA解旋酶）和eIF4G组成，eIF4G与eIF4A和eIF4E都相互作用，并增强eIF4E与帽的结合。mRNA的3'聚腺苷酸尾巴及相关的聚腺苷酸结合蛋白（PABP）也调节翻译起始，可能是通过与mRNA的5'端相互作用来实现的。在酵母和植物中，PABP与eIF4G相互作用，但在哺乳动物细胞中尚未有此类相互作用的报道。在此，我们描述了一种新的人类PABP相互作用蛋白PAIP-I，其序列与eIF4G的中央部分相似，并且与eIF4A相互作用。PAIP-1在COS-7细胞中的过表达可能通过在mRNA末端之间提供物理连接来刺激翻译。
