A homozygous point mutation in the <i>Mrps34</i> gene causes a decrease in the MRPS34 protein.

<p>(A) Schematic showing the location of the mutation in the <i>Mrps34</i> gene, mRNA and protein. The 5′- and 3′-untranslated regions are shown as grey boxes and the predicted mitochondrial targeting sequence is shown as a black box (predicted using MitoProtII, [<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1005089#pgen.1005089.ref040" target="_blank">40</a>]). Conservation of the protein sequence surrounding the mutation is highlighted with residues identical to those in the mouse sequence boxed (the mutated leucine is shown in red in the mouse sequence). Sequences used were obtained from GenBank at NCBI (human, <i>Homo sapiens</i>, NP_076425.1; chimp, <i>Pan troglodytes</i>, XP_001160122.1; monkey, <i>Macaca mulatta</i>, NP_001244544.1; mouse, <i>Mus musculus</i>, NP_081622.1; rat, <i>Rattus norvegicus</i>, NP_001099241.1; cow, <i>Bos taurus</i>, NP_001192540.1; dog, <i>Canis lupus familiaris</i>, XP_003639160.1; chicken, <i>Gallus gallus</i>, NP_001264526.1; frog, <i>Xenopus tropicalis</i>, NP_001004910.2; zebrafish, <i>Danio rerio</i>, NP_001007377.2) and the alignment was produced using ClustalW2 [<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1005089#pgen.1005089.ref041" target="_blank">41</a>]. The secondary structure of mouse MRPS34 was predicted using PSI-PRED [<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1005089#pgen.1005089.ref042" target="_blank">42</a>] and the mutated region is shown. An alpha helical region is predicted to be lost when the L68P mutation is present. (B) The mutation was confirmed by Sanger sequencing of PCR amplicons from <i>Mrps34</i>^{<i>mut/mut</i>} and littermate matched <i>Mrps34</i>^<i>wt/wt</i> mice. (C) Mutation in the nuclear gene encoding the mitochondrial MRPS34 protein leads to its decreased abundance. MRPS34 and MRPL44 protein levels were investigated in mitochondria isolated from hearts and livers of <i>Mrps34</i>^<i>wt/wt</i> and <i>Mrps34</i>^{<i>mut/mut</i>} mice by immunoblotting. Porin was used as a loading control. The data are representative of results obtained from at least 8 mice from each strain. Data are means ± SEM of three separate experiments; *, <i>p</i> < 0.05 compared with control treatments by a 2-tailed paired Student’s <i>t</i> test.