EIF3D is a protein belonging to the largest of the eukaryotic translation initiation factor family, eukaryotic translation initiation factor-3 (eIF3). eIF3 is a multiprotein complex composed of at least 13 different subunits. eIF3D binds to the 40S ribosomal subunit and thus helps in maintaining the 40S and 60S ribosomal subunits in a dissociated state. An important role of eIF3D is the formation of the 40S initiation complex by interacting with the ternary complex of eIF2/GTP/methionyl-tRNA, and promotes mRNA binding. eIF3D is the major RNA binding subunit of the eIF3 complex. It associates with the subunit p170 of eIF-3. Ubiquitous expression of eIF3D is seen in most of the tissues and it is phosphorylated upon DNA damage, likely by ATM or ATR.