In the larger context of eIF3 specialized translation pathways, eIF3d seems to play a critical role as a cap-binding protein that helps cells regulate protein synthesis even during times when the eIF3F complex (required for canonical translation) is inactivated or inhibited .
Besides the role of eIF4E as a cap-binding protein, it is reported to stimulate the helicase activity of eIF4A and aid translation of mRNAs comprising long, structured 5' UTRs .
This literature review will focus on an alternative cap-dependent translation mechanism that utilizes the eIF4E homolog eIF4E2 , a cap-binding protein that is part of a metastatic gene signature  and required for tumor growth in mouse xenografts .
eIF4F is a heterotrimeric complex composed of the cap-binding protein eIF4E, the scaffold protein eIF4G, and the RNA helicase eIF4A.
The effects of the 5' cap in mRNA translation was studied extensively and soon it was found that most eukaryotic translation is initiated with a cap-binding protein
(named later as eIF4E) that was identified by Sonenberg et al.
Pyronnet, "Phosphorylation of the cap-binding protein
eIF4E by the MAPK-activated protein kinase Mnk1," Biochemical Pharmacology, vol.
Translational control and metastatic progression: enhanced activity of the mRNA cap-binding protein
eIF-4E selectively enhances translation of metastasis-related mRNAs.