Major structural rearrangements of the canonical eukaryotic translation initiation complex

Translation initiation in eukaryotes is a complex multistep process that requires the interplay of over a dozen protein factors together with the small ribosomal subunit (SSU) and the mRNA. During all these steps, the SSU serves as a platform for attachment, displacement and release of different molecules. In recent years, the great number of high-resolution X-ray and cryo-EM structures provided unprecedented insights into the molecular mechanism of this important process in eukaryotes. More specifically, cryo-EM became a leading technique in uncovering the structural details of this process due to exceptional advances in resolution and in image processing. Here, we briefly review cap-dependent eukaryotic translation initiation with an emphasis on its major conformational changes at several key steps during the process, unraveled thanks to the recent advances in the structural biology field.