The article by Marilyn Kozak discusses the structural features of vertebrate mRNA sequences that contribute to the fidelity and efficiency of translation initiation by eukaryotic ribosomes. Five key aspects of mRNA structure are identified: the m7G cap, the context surrounding the AUG codon, the position of the AUG codon, leader length, and secondary structure. Kozak highlights that while most vertebrate mRNAs have features that ensure the fidelity of initiation, many do not appear to be designed for efficient translation. This suggests that translation may be throttled at the level of translation to regulate gene expression. The article also explores the implications of these findings for gene regulation, particularly in vertebrates, where some transcripts with encumbered 5' noncoding sequences may represent mRNA precursors rather than functional mRNAs. Additionally, the presence of GC-rich leader sequences in many regulatory genes is discussed, suggesting that these sequences may impede translation and that their regulation could be a critical component of gene control.The article by Marilyn Kozak discusses the structural features of vertebrate mRNA sequences that contribute to the fidelity and efficiency of translation initiation by eukaryotic ribosomes. Five key aspects of mRNA structure are identified: the m7G cap, the context surrounding the AUG codon, the position of the AUG codon, leader length, and secondary structure. Kozak highlights that while most vertebrate mRNAs have features that ensure the fidelity of initiation, many do not appear to be designed for efficient translation. This suggests that translation may be throttled at the level of translation to regulate gene expression. The article also explores the implications of these findings for gene regulation, particularly in vertebrates, where some transcripts with encumbered 5' noncoding sequences may represent mRNA precursors rather than functional mRNAs. Additionally, the presence of GC-rich leader sequences in many regulatory genes is discussed, suggesting that these sequences may impede translation and that their regulation could be a critical component of gene control.