The study by Marilyn Kozak analyzes 5'-noncoding sequences from 699 vertebrate messenger RNAs (mRNAs) to identify signals influencing early translation steps. The consensus sequence for initiation of translation in vertebrates is (GCC)GCCATGG, with the most highly conserved position being a purine (usually A) in the -3 position. The periodic occurrence of G in positions -3, -6, and -9 is discussed. Upstream ATG codons are rare, except in oncogene transcripts, where two-thirds have ATG codons preceding the start of the major open reading frame. Most vertebrate mRNAs have leader sequences ranging from 20 to 100 nucleotides, with longer leader sequences found in proto-oncogenes. The context around upstream ATG codons differs significantly from functional initiator codons, and the presence of these codons can inhibit translation. The study also highlights the importance of the -3 position in determining translational efficiency, with mutations in this position having the strongest influence. The findings provide insights into the mechanisms of translation initiation and the regulation of gene expression in vertebrates.The study by Marilyn Kozak analyzes 5'-noncoding sequences from 699 vertebrate messenger RNAs (mRNAs) to identify signals influencing early translation steps. The consensus sequence for initiation of translation in vertebrates is (GCC)GCCATGG, with the most highly conserved position being a purine (usually A) in the -3 position. The periodic occurrence of G in positions -3, -6, and -9 is discussed. Upstream ATG codons are rare, except in oncogene transcripts, where two-thirds have ATG codons preceding the start of the major open reading frame. Most vertebrate mRNAs have leader sequences ranging from 20 to 100 nucleotides, with longer leader sequences found in proto-oncogenes. The context around upstream ATG codons differs significantly from functional initiator codons, and the presence of these codons can inhibit translation. The study also highlights the importance of the -3 position in determining translational efficiency, with mutations in this position having the strongest influence. The findings provide insights into the mechanisms of translation initiation and the regulation of gene expression in vertebrates.