Molecular architecture of a eukaryotic translational initiation complex

Introduction: Initiation of protein synthesis is a key step in the control of gene expression. In eukaryotes, initiation is a highly complex process that requires almost a dozen protein factors. The last step involves joining of the large and small subunits of the ribosome to form the 80S initiation complex with the transfer RNA (tRNA) in the P-site base paired to the start codon. This step is cata-lyzed by the guanosine triphosphatase (GTPase) factor eIF5B. In addition, eIF5B is thought to play