AUG is the only initiation codon in eukaryotes.
An analysis of mutants of the yeast Saccharomyces cerevisiae indicates that AUG is the sole codon capable of initiating translation of iso-1-cytochrome c. This result with yeast and the sequence results of numerous eukaryotic genes indicate that AUG is the only initiation codon in eukaryotes; in contrast, results with Escherichia coli and bacteriophages indicate that both AUG and GUG are initiation codons in prokaryotes. The difference can be explained by the lack of the t6 A hypermodified nucleoside (N-[9-(beta-D-ribofuranosyl)purin-6-ylcarbamoyl]threonine) in prokaryotic initiator tRNA and its presence in eukaryotic initiator tRNA.
D002477:Cells / Q000378:metabolism*; D003062:Codon; D003575:Cytochromes c1 / Q000096:biosynthesis; D005057:Eukaryotic Cells / Q000378:metabolism*; D011387:Prokaryotic Cells / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger; D012343:RNA, Transfer / Q000032:analysis*; D012441:Saccharomyces cerevisiae / Q000648:ultrastructure
D003062:Codon; D012333:RNA, Messenger; D012343:RNA, Transfer; D003575:Cytochromes c1