ИСТИНА

Protein synthesis is a key process in all life-forms. In eukaryotes, Initiation Factor 2 (eIF2) plays an important role in translation initiation as it selects and then delivers the initiator t-RNA to the small ribosomal subunit. Under stress conditions, phosphorylation of the a-subunit of eIF2 downregulates cellular protein synthesis. However, translation of certain mRNAs continues via eIF2D dependent non-canonical initiation pathway. The molecular mechanism of this process remains elusive. In addition, eIF2D plays a role in translation re-initiation and ribosome recycling. Currently, there is not structure of eIF2D. We determined the crystal structure of the C-terminal domains of eIF2D at 1.4 Å resolution. One domain has the fold similar to that of eIF1, which is crucial for the scanning and initiation codon selection. The second domain has known SWIB/MDM2 fold, which was not observed before in other translation initiation factors. Our structure reveals atomic details of inter-domains interactions in the C-terminal part of eIF2D and shed light on the possible role of these domains in eIF2D activity in translation.