Secondary structure of mouse 28S rRNA and general model for the folding of the large rRNA in eukaryotes.

We present a secondary structure model for the entire sequence of mouse 28S rRNA (1) which is based on an extensive comparative analysis of the available eukaryotic sequences, i.e. yeast (2, 3), Physarum polycephalum (4), Xenopus laevis (5) and rat (6). It has been derived with close reference to the models previously proposed for yeast 26S rRNA (2) and for prokaryotic 23S rRNA (7-9). Examination of the recently published eukaryotic sequences confirms that all pro- and eukaryotic large rRNAs share a largely conserved secondary structure core, as already apparent from the previous analysis of yeast 26S rRNA (2). These new comparative data confirm most features of the yeast model (2). They also provide the basis for a few modifications and for new proposals which extend the boundaries of the common structural core (now representing about 85% of E. coli 23S rRNA length) and bring new insights for tracing the structural evolution, in higher eukaryotes, of the domains which have no prokaryotic equivalent and are inserted at specific locations within the common structural core of the large subunit rRNA.