title: Supernumerary proteins of mitochondrial ribosomes.
abstract: BACKGROUND
  Messenger RNAs encoded by mitochondrial genomes are translated on mitochondrial ribosomes that have unique structure and protein composition compared to prokaryotic and cytoplasmic ribosomes. Mitochondrial ribosomes are a patchwork of core proteins that share homology with prokaryotic ribosomal proteins and new, supernumerary proteins that can be unique to different organisms. In mammals, there are specific supernumerary ribosomal proteins that are not present in other eukaryotes.
  
  
  METHODS
  Here we discuss the roles of supernumerary proteins in the regulation of mitochondrial gene expression and compare them among different eukaryotic systems. Furthermore, we consider if differences in the structure and organization of mitochondrial genomes may have contributed to the acquisition of mitochondrial ribosomal proteins with new functions.
  
  
  CONCLUSIONS
  The distinct and diverse compositions of mitochondrial ribosomes illustrate the high evolutionary divergence found between mitochondrial genetic systems.
  
  
  CONCLUSIONS
  Elucidating the role of the organism-specific supernumerary proteins may provide a window into the regulation of mitochondrial gene expression through evolution in response to distinct evolutionary paths taken by mitochondria in different organisms. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.
authors: Western Australian Institute for Medical Research, Western Australia 6000, Australia; School of Chemistry and Biochemistry, The University of Western Australia, Western Australia 6009, Australia.
authors: Oliver
authors: O
authors: Rackham
authors: Western Australian Institute for Medical Research, Western Australia 6000, Australia; School of Chemistry and Biochemistry, The University of Western Australia, Western Australia 6009, Australia. Electronic address: aleksandra.filipovska@waimr.uwa.edu.au.
authors: Aleksandra
authors: A
authors: Filipovska
mesh_terms: D000818:Animals; D004194:Disease / Q000209:etiology; D005786:Gene Expression Regulation; D006801:Humans; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000502:physiology*; D012269:Ribosomal Proteins / Q000502:physiology*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*
chemical_list: D024101:Mitochondrial Proteins; D012269:Ribosomal Proteins
keywords: RNA metabolism; Ribosome; Translation