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Mago nashi proteins, integral members of the exon junction complex Members of this family, which was originally identified in Drosophila and called mago nashi, are integral members of the exon junction complex (EJC). The EJC is a multiprotein complex that is deposited on spliced mRNAs after intron removal at a conserved position upstream of the exon-exon junction, and transported to the cytoplasm where it has been shown to influence translation, surveillance, and localization of the spliced mRNA. It consists of four core proteins (eIF4AIII, Barentsz [Btz], Mago, and Y14), mRNA, and ATP and is supposed to be a binding platform for more peripherally and transiently associated factors along mRNA travel. Mago and Y14 form a stable heterodimer that stabilizes the complex by inhibiting eIF4AIII's ATPase activity. In humans, but not Drosophila, EJC is involved in nonsense-mediated mRNA decay (NMD) via binding to Upf3b, a central NMD effector. EJC is stripped off the mRNA during the first round of translation and then the complex components are transported back into the nucleus and recycled. The Mago-Y14 heterodimer has been shown to interact with the cytoplasmic protein PYM, an EJC disassembly factor, and specifically binds to the karyopherin nuclear receptor importin 13. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",