A U3 small nuclear ribonucleoprotein-requiring processing event in the 5' external transcribed spacer of Xenopus precursor rRNA.
A processing site has been identified within the 5' external transcribed spacer (ETS) of Xenopus laevis and X. borealis pre-RNAs, and this in vivo processing can be reproduced in vitro. It involves a stable and specific association of the pre-rRNA with factors in the cell extract, including at least four RNA-contacting polypeptides, yielding a distinct complex that sediments at 20S. Processing also requires the U3 small nuclear RNA. This processing, at residue +105 of the 713-nucleotide X. laevis 5' ETS, is highly reminiscent of the initial processing cleavage of mouse pre-rRNA within its 3.5-kb 5' ETS, previously thought to be mammal specific. The frog and mouse processing signals share a short essential sequence motif, and mouse factors can faithfully process the frog pre-rRNA. This conservation suggests that this 5' ETS processing site serves an evolutionarily selective function.
Mougey
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Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Pape
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Sollner-Webb
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D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D017124:Conserved Sequence; D004247:DNA; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012335:RNA, Ribosomal / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism*; D014158:Transcription, Genetic; D014982:Xenopus laevis
D012322:RNA Precursors; D012335:RNA, Ribosomal; D017411:Ribonucleoproteins, Small Nuclear; D004247:DNA