title: Evidence that eukaryotes and eocyte prokaryotes are immediate relatives.
abstract: The phylogenetic origin of eukaryotes has been unclear because eukaryotic nuclear genes have diverged substantially from prokaryotic ones. The genes coding for elongation factor EF-1 alpha were compared among various organisms. The EF-1 alpha sequences of eukaryotes contained an 11-amino acid segment that was also found in eocytes (extremely thermophilic, sulfur-metabolizing bacteria) but that was absent in all other bacteria. The related (paralogous) genes encoding elongation factor EF-2 and initiation factor IF-2 also lacked the 11-amino acid insert. These data imply that the eocytes are the closest surviving relatives (sister taxon) of the eukaryotes.
authors.affiliation: Molecular Biology Institute, University of California, Los Angeles 90024.
authors.forename: M C
authors.initials: MC
authors.lastname: Rivera
authors.forename: J A
authors.initials: JA
authors.lastname: Lake
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000235:genetics*; D001483:Base Sequence; D005075:Biological Evolution; D004269:DNA, Bacterial / Q000235:genetics; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1; D020653:Peptide Elongation Factor G; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000235:genetics*; D010445:Peptide Elongation Factors / Q000235:genetics*; D010448:Peptide Initiation Factors / Q000235:genetics*; D010802:Phylogeny; D010944:Plants / Q000235:genetics; D039881:Prokaryotic Initiation Factor-2; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004269:DNA, Bacterial; D020648:Peptide Elongation Factor 1; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D010448:Peptide Initiation Factors; D039881:Prokaryotic Initiation Factor-2; D010444:Peptide Elongation Factor Tu