The nucleotide sequences of the genes for two ribosomal proteins, H515 and HSH, from the archaeon Haloarcula marismortui, have been determined. The genes were found in a cluster together with another open reading frame with a probable regulatory function. HS15 S and HSH have counterparts in eucarya. HS15 is significantly homologous to S19 from frog (Xenopus laevis). HSH is related to S37 from yeast (Saccharomyces cerevisiae) and S27 from fly (Drosophila melanogasier), as well as to other members of the S27 family. Eubacterial counterparts were not found, suggesting, that these proteins are ‘extra proteins’ that are absent in eubacterial ribosomes.
