Figure 7.

Schematic illustration of the RaPID system. First, a non-standard macrocyclic peptide library is ribosomally synthesized from an initial random mRNA library, each of which peptide is linked to its cognate cDNA by ligation of the mRNA to the peptide via a puromycin linker. After reverse transcription, peptides that potentially bind to the target protein are then isolated by an appropriate affinity-based selection procedure. cDNAs encoding the “hit” peptides are amplified and transcribed to generate the next, enriched, library.