Mie, M., Shimizu, S., Takahashi, F. and Kobatake, E.
Notes: The authors developed an in vitro selection system that is based on ribosome display and favors identification of 5´-untranslated regions (UTRs) with high translation efficiencies. A 5´-UTR random library was created in which the 5´-UTRs were upstream of a polyhistidine-tag/Renilla luciferase-coding region. In vitro transcripts from this library were translated in vitro using the Flexi® Rabbit Reticulocyte Lysate System. The authors preferentially selected mRNAs with high translational efficiencies by shortening the translation time and capturing ternary complexes of mRNA, ribosome and nascent proteins. These complexes were captured using MagneHis™ Ni Particles. RNA was extracted from these complexes and used as a template in RT-PCR for the next round of selection. Before and after each round of selection, 9µl of RNA was translated in vitro, and 20µl of translated product was removed every 5 minutes to measure Renilla luciferase activity and monitor translation efficiency. Renilla luciferase was measured using the Renilla Luciferase Assay System. After two rounds of selection, RT-PCR products were cloned into a pUC18 vector, the sequences of the resulting plasmids were confirmed, and 0.5µg of plasmid was translated in vitro using the TNT® T7 Coupled Rabbit Reticulocyte Lysate System to further evaluate translation efficiency. (3963)