Earlier studies showed that the redundancy of ACG initiation codons enhanced the efficiency of translation initiation by 3- to 6-fold. Evidence presented here shows that this "redundancy effect" can be attributed to a favorable sequence context and, to a lesser extent, remedial initiation. In the case of redundant ACG initiator codons, the second ACG not only acts as a remedial initiation site for scanning ribosomes that skip the first ACG but also enhances the activity of the preceding initiator by providing a preferable "A" at its relative +4 position. Hence, non-successive ACG codons can be as effective as successive ACG codons in initiation, if positioned within a similar context. In contrast, redundant GUG initiation codons (GUG/GUG) bear an unfavorable "G" nucleotide at both the +4 and -3 positions relative to the first and second GUGs, respectively, such that redundant GUG codons act more poorly as translation initiation sites than does a single GUG with a favorable "A" nucleotide in the +4 position (~2.5-fold). Thus, the sequence context plays a much more important role than remedial initiation in modulating the efficiency of translational initiation from redundant non-AUG codons. © 2009 by The American Society for Biochemistry and Molecular Biology, Inc.
CITATION STYLE
Chen, S. J., Ko, C. Y., Yen, C. W., & Wang, C. C. (2009). Translational efficiency of redundant ACG initiator codons is enhanced by a favorable sequence context and remedial initiation. Journal of Biological Chemistry, 284(2), 818–827. https://doi.org/10.1074/jbc.M804378200
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