Figure 7: Novel experimental design: in vitro generation of a chimeric polypeptide containing murine alpha 1 laminin chain, initiated from the antisense RNA and non-contiguously encoded in the genome.

Uppercase letters: sense strand RNA. Lowercase letters: antisense strand RNA. Highlighted in green: AUG translation initiation codon. 5′-CAU-3′ (highlighted in blue) on the sense RNA: Complement of 5’-aug-3’ (highlighted in green) on the antisense RNA. “INS” highlighted in grey: Insert encoding a Tag peptide and lacking initiation codon; “TAG” highlighted in grey: Peptide encoded by “INS”. “ins” highlighted in grey: “INS” complement on the antisense RNA. Amino acid sequence highlighted in blue: Polypeptide encoded by conventional mRNA or by the amplified mRNA. Amino acid sequence highlighted in grey: The N-end extension of conventional polypeptide; underlined portion: Amino acids encoded by the antisense RNA. Highlighted in yellow: Editing changes resulting in replacement of the “aug” by the “aca” on the antisense RNA. Red arrowhead: Position of cleavage of the chimeric intermediate. Top panel: A-conventional mRNA encoding alpha 1 chain of laminin. B-chimeric RNA end product of amplification (adapted from Figure 1) encoding the same polypeptide as “A”. C-amino acid sequence encoded by either “A” or “B”. Middle panel: A-projected edited “dormant” mRNA originated from edited alpha 1 laminin gene. B-antisense complement of edited alpha 1 laminin mRNA. C-folding of the antisense strand into self-priming configuration; 3’terminal “c” is a transcript of the 5’capG of mRNA. D-extension of self-primed antisense strand into sense-oriented sequence followed by strand separation and cleavage of the chimeric intermediate. E-chimeric RNA end product of RNA-dependent amplification of edited alpha 1 laminin mRNA. F-projected translational outcome. Bottom panel: Same as the middle panel with the exception of editing changes resulting in replacement of the “aug” by the “aca” (highlighted in yellow) on the antisense RNA.