Eukaryotic translation initiation factor 4G (eIF4G) (eIF4G; eIF4G1 (human isoform))

Eukaryotic translation initiation factor 4G (eIF4G) is a large multidomain scaffolding protein (approximately 175 kDa in humans) that serves as the central organizational hub of the eIF4F translation initiation complex. This complex, which includes the cap-binding protein eIF4E and the RNA helicase eIF4A, is essential for recognizing the 5' methylguanosine cap on mRNA and recruiting the small ribosomal subunit to initiate protein synthesis. Beyond its core translation initiation role, eIF4G participates in mRNA circularization through interactions with poly(A)-binding proteins, enhances translation efficiency, and functions in nonsense-mediated decay and reinitiation processes. As a key regulator of translation in eukaryotes—a process tightly linked to cell growth and proliferation—eIF4G has emerged as an attractive therapeutic target for cancer, where dysregulated translation drives malignant transformation. Small-molecule inhibitors such as 4EGI-1 have been designed to disrupt the eIF4E-eIF4G interaction through allosteric mechanisms, offering a strategy to selectively suppress cap-dependent translation in cancer cells, though the essential role of eIF4G in normal protein synthesis raises safety considerations regarding broad cellular toxicity.

Other names

eIF4G1p220 (older nomenclature, referring to its apparent molecular weight on SDS-PAGE)eIF4GIeIF4GII (mammalian isoform)

Disruption of eIF4F complex assembly: Blocking eIF4E-eIF4G interaction to prevent formation of the functional translation initiation complex Inhibition of translation initiation: Preventing recruitment of ribosomal pre-initiation complexes to mRNA 5' ends Suppression of cap-dependent translation: Reducing protein synthesis from mRNA with 5' cap structures Allosteric modulation: Small-molecule inhibitors like 4EGI-1 induce conformational changes that prevent eIF4G binding while stabilizing 4EBP repressor binding