Translational initiation factors IF-1 and eIF-2 alpha share an RNA-binding motif with prokaryotic ribosomal protein S1 and polynucleotide phosphorylase.
Initiation of translation is a complicated process involving numerous accessory factors whose functions remain incompletely understood. Bacterial ribosomal protein S1 is known to contain a repeated sequence motif (S1-RM), also found in polynucleotide phosphorylase, that is thought to be involved in binding to RNA. Using the technique of profile analysis, the S1-RM can also be found in bacterial and chloroplast translation initiation factor IF-1 sequences, and in the sequences of eukaryotic translation initiation factor eIF-2 alpha chains. The significance of the similarity of the sequences is very high suggesting that the occurrence of the S1-RM in these diverse proteins represents homology. The similarity of S1 to IF-1 further suggests that S1 has evolved from an IF-1 like ancestor, and therefore that the two proteins have a similar or competitive function. The most obvious common function of the proteins containing the S1-RM seems to be RNA binding, suggesting that IF-1 and eIF-2 alpha may bind to RNA.
Gribskov
M
M
National Cancer Institute, Frederick Cancer Research and Development Center, ABL-Basic Research Program, MD.
D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites; D015977:Eukaryotic Initiation Factor-1 / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D011117:Polyribonucleotide Nucleotidyltransferase / Q000378:metabolism*; D039861:Prokaryotic Initiation Factor-1; D012313:RNA / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid; D012269:Ribosomal Proteins / Q000378:metabolism*; D017385:Sequence Homology
D001426:Bacterial Proteins; D015977:Eukaryotic Initiation Factor-1; D039861:Prokaryotic Initiation Factor-1; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; C015494:ribosomal protein S1; D012313:RNA; D011117:Polyribonucleotide Nucleotidyltransferase