On the origin of the cap-dependent initiation of translation in eukaryotes.
The Shine-Dalgarno sequence of prokaryotic mRNAs, which helps to bind and position the ribosome at the start site for protein synthesis, is absent from eukaryotic mRNAs. Instead, for most, a structure at the 5' end and a much larger number of protein initiation factors are needed for both binding of the ribosome and for successful start-site selection, that is, a 'cap-dependent' initiation mechanism. Although the mechanics of this process are well studied, what is not clear is how it evolved. By analyzing recent progress in different fields, I suggest that it was the need to adjust to the arrival of the nuclear membrane and the subsequent requirement to export intron-less mRNAs to the cytoplasm that spurred the shift to the more complex translation initiation mechanism in eukaryotes.
Hernández
Greco
G
Department of Biology, McGill University, 1205 Dr. Penfield, Montreal, QC. H3A 1B1, Canada. greco.hernandez@mcgill.ca
D000818:Animals; D005057:Eukaryotic Cells / Q000378:metabolism*; D006801:Humans; D010442:Peptide Chain Initiation, Translational; D012315:RNA Caps / Q000235:genetics / Q000378:metabolism*; D020365:RNA Helicases / Q000378:metabolism
D012315:RNA Caps; D020365:RNA Helicases