Eukaryotic ribosomes can recognize preproinsulin initiation codons irrespective of their position relative to the 5' end of mRNA.
The functional assay of a eukaryotic mRNA, into which additional AUG codons have been introduced by in vitro mutagenesis, shows that a translational initiation site need not necessarily be the nearest AUG codon to the 5' end of a mRNA. Hence, the sequence surrounding the AUG, and not simply its position relative to the 5' end of mRNA, appears to be important in determining initiation efficiency.
D000818:Animals; D001483:Base Sequence; D002474:Cell-Free System; D002872:Chromosome Deletion; D003062:Codon; D005818:Genetic Engineering; D007328:Insulin; D009154:Mutation; D010442:Peptide Chain Initiation, Translational; D011384:Proinsulin / Q000235:genetics*; D011498:Protein Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D012270:Ribosomes / Q000378:metabolism*
D003062:Codon; D007328:Insulin; D011498:Protein Precursors; D012333:RNA, Messenger; C013737:preproinsulin; D011384:Proinsulin