eIF4GII

eIF4GII, also known as eIF4G2, is a eukaryotic translation initiation factor that functions as a scaffold in cap-dependent translation initiation. In vertebrates, it is one of two major eIF4G paralogs, the other being eIF4GI. The human EIF4G2 gene encodes this protein. eIF4GII assembles with the cap-binding protein eIF4E, the RNA helicase eIF4A, and the adaptor complex eIF3 to form a translation initiation platform that supports recruitment of the 40S ribosomal subunit to the mRNA 5' end. It also interacts with the poly(A)-binding protein (PABP), contributing to the formation of a closed-loop mRNA conformation that enhances translation efficiency and mRNA stability.

Although eIF4GII shares core architectural features with eIF4GI, it exhibits functional specialization. eIF4GII can participate in global cap-dependent translation but is also implicated in the translation of a subset of mRNAs, particularly under certain cellular conditions such as stress or developmental contexts, where translation may be selectively regulated or maintained when other initiation pathways are constrained. The relative contribution of eIF4GII versus eIF4GI appears to vary by cell type and organism.

eIF4GII is widely expressed in human tissues and contributes to translational regulation in multiple contexts. While its exact roles are still being refined, research indicates that eIF4GII can influence how cells modulate protein synthesis in response to changing conditions, including cellular stress and disease models. Its study helps illuminate the diversity and redundancy within the eIF4G family of initiation factors.