Translational modulation in vitro of a eukaryotic viral mRNA encoding overlapping genes: ribosome scanning and potential roles of conformational changes in the P/C mRNA of Sendai virus.

Expression of proteins from three overlapping genes in a single mRNA species of Sendai virus was modulated in a cell-free rabbit reticulocyte translation system. Hybrid-arrested translation by oligodeoxynucleotides complementary to specific regions of the mRNA that specifies the viral P, C, and C' proteins demonstrated that ribosomes scan the RNA from its 5' end to find initiation codons, and suggested that the secondary structure of the mRNA influences the selection of alternative initiation codons. Translational modulation of P, C, and C' proteins by Mg++ and spermidine indicated that RNA folding is involved in this selection process.