EIF3J (Eukaryotic translation initiation factor 3 subunit J) belongs to the EIF-3 subunit J family. EIF3 plays a central role in binding of initiator methionyl-tRNA and mRNA to the 40S ribosomal subunit to form the 40S initiation complex. EIF3J binds to the aminoacyl (A) site and mRNA entry channel of the 40S subunit, placing EIF3J directly in the ribosomal decoding center. EIF3J also interacts with eIF1A and reduces 40S subunit affinity for mRNA. A high affinity for mRNA is restored upon recruitment of initiator tRNA, even though EIF3J remains in the mRNA-binding cleft in the presence of tRNA. Recombinant human EIF3J protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.