CGA codon pairs are more inhibitory than single CGA codons. (A,B) The effects of the arrangement of five CGA codons within an (Arg)10 insert on Renilla luciferase activity were compared to each other and to Renilla luciferase activity from constructs containing (Arg)10 insertions specified by (AGA)10 or (CGA)10. (A) The arrangements of Arg CGA codons with the number of CGA codons and codon pairs indicated and (B) the resulting luciferase activity with lanes corresponding to constructs in A. Reported values were corrected to an independently transcribed firefly luciferase gene, and then normalized to (AGA)10. (C) Schematic of the arrangement of CGA codons in test constructs designed to examine the effects of single CGA codons, pairs of CGA codons, and alternating CGA codons. (D) Relative luciferase activity of firefly luciferase reporter constructs containing (Arg)16 insertions with increasing CGA content arranged either as single codons or codon pairs. Reported values were corrected to an independently transcribed Renilla luciferase gene, and then normalized to (AGA)16. (E) Relative luciferase activity of Renilla luciferase reporter constructs containing (Arg)16 insertions with increasing CGA content arranged either as single codons or codon pairs. Reported values were corrected to an independently transcribed firefly luciferase gene, and then normalized to (AGA)16. (F) Relative luciferase activity of Renilla luciferase reporter constructs containing (Arg)16 insertions with increasing CGA content. CGA codons are clustered either as single codons separated by two AGA codons or as alternating codons (CGA–AGA). Reported values were corrected to an independently transcribed firefly luciferase gene, and then normalized to (AGA)16.
