Eocytes: a new ribosome structure indicates a kingdom with a close relationship to eukaryotes.

Publisher Website
Google Scholar
Abstract
Ribosomal large and small subunits are organized in 4 general structural patterns. The 4 types are found in ribosomes from eubacteria, archaebacteria, eukaryotes and a group of S-dependent bacteria (eocytes), respectively. All 4 ribosomal types share a common structural core, but each type also has additional independent structural features. The independent features include the eukaryotic lobes and the archaebacterial bill on the smaller subunit. On the larger subunit, they include the eocytic lobe, eocytic gap and eocytic bulge and a modified central protuberance. These data are most parsimoniously fit by a single, unrooted evolutionary tree. In this tree, eocytes are closely related to eukaryotes: archaebacteria and eubacteria are closest neighbors. The tree is consistent with currently known molecular biological properties and indicates that eocytes have a phylogenetic importance equal to that of the 3 known kingdoms. When other properties and molecular mechanisms of these organisms are better defined, an appropriate kingdom name for this group might be the Eocyta.