Biology

Dr. Tanweer Hussain
MRC Laboratory of Molecular Biology, Cambridge, UK

Translation initiation in eukaryotes begins with the formation of a pre-initiation complex (PIC) containing the 40S ribosomal subunit and eukaryotic initiation factors (eIFs): eIF1, eIF1A, eIF3, ternary complex (eIF2-GTP-Met-tRNAi) and eIF5. The PIC attaches to the 5’ end of the mRNA in collaboration with eIF4 complex. Subsequently, it scans the 5’ UTR to locate the start codon, whereupon it isomerizes to a scanning-arrested conformation. We have determined multiple single particle cryo-electron microscopy (cryo-EM) reconstructions of 48S PICs from yeast, each proposed to represent a distinct step along the initiation pathway, thus elucidating key events in start codon recognition.