Protein tagging at rare codons is caused by tmRNA action at the 3′ end of nonstop mRNA generated in response to ribosome stalling

Schematic drawing and sequences of the crp variants containing clusters of arginine codons. The black box represents the CRP ORF. The nucleotide sequence and amino acid sequence (in one-letter code) of the 3′ portion of the crp gene derived from pHA7M are shown below the diagram. The clusters of five arginine codons were inserted after the last codon of CRP (Arg 209) or the codon for Val 205. The sequence of five consecutive arginine codons are shown in italic along with plasmid and protein names.