EIF1B is crucial for the scanning process in vitro. During the scanning process, EIF1B is a component of a complex involved in recognition of the initiator codon. Translation is also initiated by the role of EIF1B in regulating the activity of ribosomal subunits 43S, 48S and 40S. This protein enables 43S ribosomal complexes to discern between cognate and near-cognate initiation codons, sensing the nucleotide content of initiation codons.