Editing Codon usage bias (section)

=== Effect on RNA secondary structure ===
Because [[nucleic acid secondary structure|secondary structure]] of the [[5' end|5’ end]] of mRNA influences translational efficiency, synonymous changes at this region on the mRNA can result in profound effects on gene expression. Codon usage in [[noncoding DNA]] regions can therefore play a major role in RNA secondary structure and downstream protein expression, which can undergo further selective pressures. In particular, strong secondary structure at the [[ribosomal binding site|ribosome-binding site]] or [[start codon|initiation codon]] can inhibit translation, and mRNA folding at the 5’ end generates a large amount of variation in protein levels.<ref name = "pmid22921354">{{Cite journal
 | pmid = 22921354
| year = 2012
| last1 = Novoa
| first1 = E. M.
| title = Speeding with control: Codon usage, tRNAs, and ribosomes
| journal = Trends in Genetics
| volume = 28
| issue = 11
| pages = 574–81
| last2 = Ribas De Pouplana
| first2 = L
| doi = 10.1016/j.tig.2012.07.006
}}</ref>