Conservation of the primary structure at the 3′ end of 18S rRNA from eucaryotic cells

Sequence of the 3′‐terminal domain of mouse 18 S rRNA

“…Our data are in full agreement with a previous partial determination involving reverse transcription of in vitro polyadenylated mouse 18 S rRNA [26]. Since reverse transcriptase cannot proceed through m6A-m6A residues, sequence determinations in that work was limited to the 20 3'-terminal nucleotides.…”

“…Firstly, most of the differences are located in an area (segment 56-77, distal to 3'-endlabelled RNA-terminus) where resolution is rather low in the direct RNA sequencing approach: 5 differences correspond to nucleotides undetected in [27] while they have identified as G nucleotides 37, 59 and 63 (C, here). They also found an extra G (position 7) that we have not detected; this nucleotide was not detected any more when mouse 18 S rRNA was reverse-transcribed [26] and does not exist in another independently cloned mouse rDNA fragment [28], as indicated by the presence of the Sau3A restriction site (recognition sequence GATC) in identical location as compared with our pMEB3 cloned fragment. This G is not present either in the rat 18 S rRNA as demonstrated by sequencing of a 32 nucleotide-long rRNA fragment (segment 5-36) after in vitro terminal labelling [29] or by homochromatography fingerprinting of total T 1 RNase oligonucleotides of 18 S rRNA [30].…”

“…The complete sequence of mouse internal transcribed spacers will be described elsewhere (in preparation). Due to availability of a short nucleotide sequence from the 3'-terminus of mouse 18 S rRNA [26,27], the experimental mapping of the terminus of 18 S rRNA coding sequences was not necessary, as was con- .lc), most of the sequence was actually confirmed by independent determinations on both strands.…”

3'‐terminal nucleotide sequence of Crithidia fasciculata small ribosomal subunit RNA

“…The band spacings in fig.1 provide evidence of modified residues at positions 3,20,21,54 and 65. While these remain to be definitely characterized, some deductions about their identities can be made.…”

“…In fact, specific complexes between prokaryotic 16 S rRNA and mRNA [ 14,151, eukaryotic 18 S rRNA and mRNA [ 161, and eukaryotic 18 S rRNA and 5 S rRNA [ 12,171 have been observed, and possible sites of interaction in these complexes have been inferred from sequence data [2,9-l 1,13-16,181. However, with the exception of the mRNA binding site in Escherichia coli 16 S rRNA [ 19,201 and the 18 S rRNA binding site in wheat 5 S rRNA [21], there is as yet little direct evidence supporting the particular sequences which are supposed Abbreviation: SSU RNA, small ribosomal subunit RNA (16 S rRNA in prokaryotes,18 S rRNA in eukaryotes) 298 to interact in the various proposed complexes between SSU RNA and other RNAs.…”