This is the conserved N-terminus and central portion of the mitochondrial small subunit 28S ribosomal protein S22. Mammalian mitochondria carry out the synthesis of 13 polypeptides that are essential for oxidative phosphorylation and, hence, for the synthesis of the majority of the ATP used by eukaryotic organisms. The number of proteins produced by prokaryotes is smaller, reflected in the lower number of ribosomal proteins present in them [1].

1: A proteomics approach to the identification of mammalian mitochondrial small subunit ribosomal proteins. Koc EC, Burkhart W, Blackburn K, Moseley A, Koc H, Spremulli LL; J Biol Chem 2000;275:32585-32591. PMID:10938081