Preferential translation of mRNAs in an mRNA-dependent reticulocyte lysate.

Messenger RNA competition experiments were performed in an mRNA-dependent reticulocyte lysate using three kinds of mRNA: rabbit globin mRNA, calf eye lens mRNA and RNA of turnip yellow mosaic virus. Our results indicate that at supersaturating concentrations of mRNA preferential translation of certain mRNA species can be observed. Furthermore, the pattern of mRNA selection by the translational apparatus suggests that the rate of translation of different mRNA species is limited by different components of the reticulocyte lysate. Our observations n the cell-free system are strikingly different from our previously published mRNA competition experiments in Xenopus oocytes using the same preparations of lens and globin mRNA, in which no selective translation was observed [Asselbergs et al., Eur. J. Biochem. 94, 249-254 (1979)]. The restraints on mRNA translation in vitro are apparently different from those in vivo, i.e. in oocytes.