Unwinding RNA for protein synthesis During the first steps of protein synthesis, the small subunit of the ribosome scans the 5′ end of the mRNA, looking for the protein start codon. This process involves one of the translation initiation factors, eIF4A, which helps to remove any RNA structures that might impede the ribosome's search. García-García et al. used single-molecule optical trap assays to show that eIF4A, in combination with two other translation initiation factors, is able to continuously and directionally unwind a double-stranded RNA hairpin. The factors unwound RNA in steps roughly equal to a turn of the RNA double helix. Science , this issue p. 1486