Fig. 2.

The recombined txnrd1⁻ allele issues a non-translated mRNA. a, schematic. Predicted mRNAs from the wild-type and null alleles are shown. Diagonostic RT-PCR primer pairs and the sizes of expected products are indicated. RT-PCR-based cloning of Txnrd1 cDNAs from heterozygous mouse kidney RNA samples indicated that exon 0 spliced precisely to exon 3 (data not shown). The first two ATGs initiate short out-of-Txnrd1-frame ORFs that would issue predicted oligopeptides of 13 (-1 frame) and 8 (+1 frame) amino acids, respectively (first ATG generated by the exon 0/3 splice junction). The third ATG is in the Txnrd1 reading frame, at Met⁷⁰ in exon 3. Due to context (AAGCTGATGC), this ATG is predicted to not function as an initiator. b, translational efficiency of Txnrd1⁺ and Txnrd1⁻ mRNAs in heterozygous mouse liver. At top is shown an absorbance scan of a representative liver polysome gradient with the positions of ribonucleoprotein particles (RNP) and polysomes indicated above and the positions of gradient fractions indicated below. Below are RT-PCR analyses of the positions of Txnrd1 mRNAs in a heterozygous mouse liver polysome gradient using the PCR primer sets indicated in panel a.