Causes and consequences of mitochondrial proteome size-variation in animals

Despite a conserved set of core mitochondrial functions, animal mitochondrial proteomes show a large variation in size. In this study, we analyzed the putative mechanisms behind and functional significance of this variation using experimentally-verified mt-proteomes of four bilaterian animals and two non-animal outgroups. We found that, of several factors affecting mitochondrial proteome size, evolution of novel mitochondrial proteins in mammals and loss of ancestral proteins in protostomes were the main contributors. Interestingly, gain and loss of conventional mitochondrial targeting signals was not a significant factor in the proteome size evolution.