Mitochondrial ribosomal proteins (MRPs) are essential components for the structural and functional integrity of the mitoribosome complex. Throughout evolution, the mammalian mitoribosome has acquired new Mrp genes to compensate for loss of ribosomal RNA. More than 80 MRPs have been identified in mammals. Here we document expression pattern of 79 Mrp genes during mouse development and adult tissues and find that these genes are consistently expressed throughout early embryogenesis with little stage or tissue specificity. Further investigation of the amino acid sequence reveals that this group of proteins has little to no protein similarity. Recent work has shown that the majority of Mrp genes are essential resulting in early embryonic lethality, suggesting no functional redundancy among the group. Taken together, these results indicate that the Mrp genes are not a gene family descended from a single ancestral gene, and that each MRP has unique and essential role in the mitoribosome complex. The lack of functional redundancy is surprising given the importance of the mitoribosome for cellular and organismal viability. Further, these data suggest that genomic variants in Mrp genes may be causative for early pregnancy loss and should be evaluated as clinically.

线粒体核糖体蛋白 (MRP) 是线粒体复合体结构和功能完整性的重要组成部分。在整个进化过程中，哺乳动物线粒体获得了新的Mrp基因以补偿核糖体 RNA 的损失。已经在哺乳动物中鉴定了 80 多种 MRP。在这里，我们记录了 79 个Mrp基因在小鼠发育和成年组织期间的表达模式，并发现这些基因在整个早期胚胎发生过程中始终如一地表达，几乎没有阶段或组织特异性。对氨基酸序列的进一步研究表明，这组蛋白质几乎没有蛋白质相似性。最近的工作表明，大多数Mrp基因是必不可少的，导致早期胚胎致死，这表明该组之间没有功能冗余。综上所述，这些结果表明Mrp基因不是一个源自单个祖先基因的基因家族，并且每个 MRP 在 mitoribosome 复合物中都具有独特而重要的作用。鉴于核糖体对细胞和生物体活力的重要性，功能冗余的缺乏令人惊讶。此外，这些数据表明，Mrp基因中的基因组变异可能是导致早期流产的原因，应进行临床评估。