Disease relevance of U3snRNA

• We found that the highly conserved region of U6 snRNA and the catalytic domain of (-)sTRSV are strikingly similar in structure to the catalytic core region of the group I self-splicing intron in cyanobacteria [1].

High impact information on U3snRNA

• Splicing of several genes is normal in these strains, ruling out an essential base pairing between U1 snRNA and 3' splice sites [2].
• In mammalian cells, there are six major molecular species (U1 to U6 snRNA), which are complexed with proteins, forming small nuclear ribonucleoprotein particles, snRNPs [3].
• There exist two regions of extended primary sequence identity between S. pombe and human U1 RNAs; the first comprises nucleotides involved in hydrogen bonding to 5' splice junctions, and the second is a single-stranded region which, in the human snRNA, forms part of the A protein binding site [4].
• The 3'-end modification of the optimal synthetic substrate was identical to that observed with endogenous U6 snRNA isolated from HeLa cells [5].
• Discovery of mRNA-type introns in the highly conserved region of the U6 snRNA genes led to the hypothesis that U6 snRNA functions as a catalytic element during pre-mRNA splicing [1].

Biological context of U3snRNA

• We have sequenced the 5' flanking region of the U2 gene and compared this with the 5' flanking sequences of other snRNA genes from Schizosaccharomyces pombe [6].
• Thirty-three nucleotides of 5' flanking sequence including the 'TATA' box are necessary and sufficient for efficient U2 snRNA transcription in Schizosaccharomyces pombe [6].
• The two sites previously shown to be crosslinked to U3 snRNA as well as the previously proposed recognition site for processing and one of the early processing site (based on sequence homology to the vertebrate ETS cleavage site) are located in single-stranded regions in the model [7].
• The significance of a short conserved sequence just downstream of the U3A and U3B genes is unknown, as it is not found 3' to other snRNA coding sequences in S. pombe [8].

Anatomical context of U3snRNA

• Pre-mRNA processing takes place within the spliceosome, a dynamic structure composed of small nuclear RNA (snRNA) and proteins [9].

Other interactions of U3snRNA

• A notable exception is a 19-bp block, centered 36 nucleotides upstream from the transcriptional start site, in which the two loci match in 15 positions; this motif may represent an RNA polymerase II upstream regulatory element, because related sequences are found preceding fission yeast U1, U2, U4, and U5 snRNA genes [8].
• Rescue of the fission yeast snRNA synthesis mutant snm1 by overexpression of the double-strand-specific Pac1 ribonuclease [10].

Analytical, diagnostic and therapeutic context of U3snRNA

• The complexity of the trimethylguanosine-capped, small nuclear RNA (snRNA) populations in a number of organisms has been examined using immunoprecipitation and two-dimensional gels [11].
• The bank was screened by Northern blot analysis with probes complementary to S. pombe U6 small nuclear RNA (sn RNA), the gene for which has a splicesomal (mRNA-type) intron [12].

References