Yeast Eukaryotic Initiation Factor 4B Remodels the MRNA Entry Site on the Small Ribosomal Subunit.

Eukaryotic Initiation Factor 4 (eIF4) is a group of factors that activates mRNA for translation and recruit 43S preinitiation complex (PIC) to the mRNA 5' end, forming the 48S PIC. The eIF4 factors include mRNA 5' cap-binding protein eIF4E, ATP-dependent RNA helicase eIF4A, and scaffold protein eIF4G, which anchors eIF4A and eIF4E. Another eIF4 factor, eIF4B, stimulates the RNA helicase activity of eIF4A and facilitates mRNA recruitment.

mRNA Recruiting eIF4 Factors Involved in Protein Synthesis and Its Regulation.

The recruitment of mRNA onto the ribosome affects not only global translation but also the spatial and temporal fine-tuning of eukaryotic translation initiation. The eukaryotic initiation factor 4 (eIF4) factors, namely, eIF4G, eIF4E, eIF4A, and eIF4B, facilitate the recruitment of mRNA onto the preassembled 43S pre-initiation complex (PIC), thus leading to the formation of the 48S PIC. Several biochemical and genetic studies have established the roles of eIF4 factors; however, the available structural information is limited.