Universally conserved translation initiation factors

Multiple sequence alignment of bacterial IF-1, eukaryotic eIF-1A, and their archaeal homologs (aIF-1A). Positions in which sequence conservation is >50% identity are highlighted in black. The last line is a consensus of the six S1 motifs found in E. coli ribosomal protein S1: highlighted uppercase type denotes those residues that are also highly conserved in the IF-1/eIF-1A/aIF-1A family, whereas highlighted lowercase type denotes the residues for which a related amino acid occurs in the family. (Dots denote nonconserved positions in the S1 consensus, and dashes denote gaps/insertions of more than one residue.) The horizontal arrows display the positions of the β-strands according to the three-dimensional structure (33). Protein names (and accession number—when different) are as follows: IF1_ECOLI, E. coli IF-1; IF1-SYNEC, Synechocystis sp. IF-1 (EMBL:D90905_47); IF1_BACSU, Bacillus subtilis IF-1; IF1-DEIRA, unpublished ORF from Deinococcus radiodurans; IF1A_METJA, Methanococcus jannaschii aIF-1A; IF1A-METTH, Methanobacterium thermoautotrophicum unpublished ORF; IF1A-ARCFU, Archaeoglobus fulgidus unpublished ORF; YRP2_THEAC, Thermoplasma acidophilum hypothetical protein; IF1A_WHEAT, Triticum aestivum eIF-1A; IF1A_HUMAN, human eIF-1A; IF1A_RABIT, Oryctolagus cuniculus eIF-1A; IF1A_YEAST, Saccharomyces cerevisiae eIF-1A.