The complete amino acid sequence of the ribosomal protein HS3 from Halobacterium marismortui, an archaebacterium

The complete amino acid sequence of the ribosomal protein HS3 from Halobacterium marismortui has been determined, which is, to our knowledge, the first complete protein sequence from an archaebacterial ribosome. Comparison of the primary structure of HS3 with all sequenced ribosomal proteins from other organisms revealed that HS3 is significantly homologous with protein S9 from the gram-negative Escherichia coli and the gram-positive Bacillus stearothermophilus, having 27 and 37% identical residues, respectively. Based on these and other results it is possible that some ribosomal components of archaebacteria are related to eubacteria, especially gram-positive bacteria, and others to eukaryotes.