The complete amino acid sequence of ribosomal protein H‐S11 from the archaebacterium Halobacterium marismortui

The complete amino acid sequence of ribosomal protein H‐S11 from the extremely halophilic archaebacterium Halobacterium marismortui is presented. This has been achieved by the sequence analysis of peptides derived by enzymatic digestions with trypsin, pepsin and Staphylococcus aureus protease, as well as by chemical cleavage with cyanogen bromide and o ‐iodosobenzoic acid. The protein consists of 155 amino acid residues and has a molecular mass of 17545 Da. Comparison of this sequence with other ribosomal proteins by the computer programmes RELATE and ALIGN showed that the C‐terminal two‐thirds of H‐S11 is homologous to the eubacterial ribosomal protein S15 and that the N‐terminal one‐third of H‐S11 is possibly related to the N‐terminal region of the eubacterial ribosomal protein S8. To explain this finding, possible genetic events during evolution, e.g. fusion or splitting of genes, are discussed.