Universal conservation in translation initiation revealed by human and archaeal homologs of bacterial translation initiation factor IF2.
Binding of initiator methionyl-tRNA to ribosomes is catalyzed in prokaryotes by initiation factor (IF) IF2 and in eukaryotes by eIF2. The discovery of both IF2 and eIF2 homologs in yeast and archaea suggested that these microbes possess an evolutionarily intermediate protein synthesis apparatus. We describe the identification of a human IF2 homolog, and we demonstrate by using in vivo and in vitro assays that human IF2 functions as a translation factor. In addition, we show that archaea IF2 can substitute for its yeast homolog both in vivo and in vitro. We propose a universally conserved function for IF2 in facilitating the proper binding of initiator methionyl-tRNA to the ribosomal P site.
Lee
J H
JH
Laboratory of Eukaryotic Gene Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2716, USA.
Choi
S K
SK
Roll-Mecak
A
A
Burley
S K
SK
Dever
T E
TE
D000595:Amino Acid Sequence; D001105:Archaea / Q000235:genetics*; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D017124:Conserved Sequence; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry* / Q000235:genetics*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors; D010802:Phylogeny; D039881:Prokaryotic Initiation Factor-2; D014176:Protein Biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics
D019843:Archaeal Proteins; D001426:Bacterial Proteins; D015852:Eukaryotic Initiation Factor-2; C118735:IF2 protein, archaeal; D010448:Peptide Initiation Factors; D039881:Prokaryotic Initiation Factor-2