ATP-binding RNA helicase involved in translation initiation. Part of the 43S pre-initiation complex that is required for efficient initiation on mRNAs of higher eukaryotes with structured 5'-UTRs by promoting efficient NTPase-dependent 48S complex formation. Specifically binds to the 40S ribosome near the mRNA entrance. Does not possess a processive helicase activity. ATP + H2O = ADP + H(+) + phosphate Part of the 43S pre-initiation complex (PIC) that contains at least Met-tRNA, EIF1, EIF1A (EIF1AX or EIF1AY), EIF2S1, EIF2S2, EIF2S3, EIF3A, EIF3B, EIF3C, EIF3D, EIF3E, EIF3F, EIF3G, EIF3H, EIF3I, EIF3J, EIF3K, EIF3L, EIF3M, DHX29 and the 40S ribosomal subunit. Belongs to the DEAD box helicase family. DEAH subfamily.