A novel shuttling protein, 4E-T, mediates the nuclear import of the mRNA 5 ' cap-binding protein, eIF4E

作者：Dostie J; Ferraiuolo M; Pause A; Adam SA; Sonenberg N^*

来源：The EMBO Journal, 2000, 19(12): 3142-3156.

DOI：10.1093/emboj/19.12.3142

• cap-binding protein
• eIF4E localization
• initiation factor
• shuttling protein
• transport

The eukaryotic translation initiation factor 4E (eIF4E) plays an important role in the control of cell growth. eIF4E binds to the mRNA 5' cap structure m(7)GpppN (where N is any nucleotide), and promotes ribosome binding to the mRNA in the cytoplasm. However, a fraction of eIF4E localizes to the nucleus. Here we describe the cloning and functional characterization of a new eIF4E-binding protein, referred to as 4E-T (eIF4E-Transporter) We demonstrate that 4E-T is a nucleocytoplasmic shuttling protein that contains an eIF4E-binding site, one bipartite nuclear localization signal and two leucine-rich nuclear export signals. eIF4E forms a complex with the importin alpha beta heterodimer only in the presence of 4E-T. Overexpression of wild-type 4E-T, but not of a mutant defective for eIF4E binding, causes the nuclear accumulation of HA-eIF4E in cells treated with leptomycin B. Taken together, these results demonstrate that the novel nucleocytoplasmic shuttling protein 4E-T mediates the nuclear import of eIF4E via the importin alpha beta pathway by a piggy-back mechanism.

• 出版日期2000-6-15
• 单位西北大学