Plays a role in translation initiation (, ). Ribosome-dependent GTPase that promotes the joining of the 60S ribosomal subunit to the pre-initiation complex to form the 80S initiation complex with the initiator methionine-tRNA in the P-site base paired to the start codon (, ). Together with eIF1A (EIF1AX), actively orients the initiator methionine-tRNA in a conformation that allows 60S ribosomal subunit joining to form the 80S initiation complex (, ). Is released after formation of the 80S initiation complex . Its GTPase activity is not essential for ribosomal subunits joining, but GTP hydrolysis is needed for eIF1A (EIF1AX) ejection quickly followed by EIF5B release to form elongation-competent ribosomes (, ). In contrast to its procaryotic homolog, does not promote recruitment of Met-rRNA to the small ribosomal subunit .
Subcellular locations: Cytoplasm