U1 spliceosomal RNA
U1 spliceosomal RNA is the small nuclear RNA (snRNA) component of U1 snRNP (small nuclear ribonucleoprotein), an RNA-protein complex that combines with other snRNPs, unmodified pre-mRNA, and various other proteins to assemble a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs. Splicing, or the removal of introns, is a major aspect of post-transcriptional modification, and takes place only in the nucleus of eukaryotes.
The U1 snRNP recognizes and binds to the sequence of the 5'-splice site of an intron in a strand of pre-mRNA. Experimentation has demonstrated that the binding of U1 snRNA to the 5'-splice site is required, but not sufficient, to begin spliceosome assembly. [1]
There are significant differences in sequence and secondary structure between metazoan and yeast U1 snRNAs, the latter being much longer (568 nucleotides as compared to 164 nucleotides in humans). Nevertheless, secondary structure predictions suggest that all U1 snRNAs share a 'common core' consisting of helices I, II, the proximal region of III, and IV.[2] This family does not contain the larger yeast sequences.
References
Further reading
- Oubridge, C; Ito N, Evans PR, Teo CH, Nagai K (1994). "Crystal structure at 1.92 A resolution of the RNA-binding domain of the U1A spliceosomal protein complexed with an RNA hairpin". Nature 372 (6505): 432–438. doi:10.1038/372432a0. PMID 7984237.
- Katsamba, PS; Myszka DG, Laird-Offringa IA (2001). "Two functionally distinct steps mediate high affinity binding of U1A protein to U1 hairpin II RNA". J Biol Chem 276 (24): 21476–21481. doi:10.1074/jbc.M101624200. PMID 11297556.
External links
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| Nuclear |
Precursor mRNA · 5' cap formation · Polyadenylation (CPSF, CstF, PAP, PAB2, CFI, CFII) · Poly(A)-binding protein
RNA splicing: intron/exon · snRNP · spliceosome (minor spliceosome, U1) · alternative splicing · pre-mRNA processing factor (PLRG1, PRPF3, PRPF4, PRPF4B, PRPF6, PRPF8, PRPF18, PRPF19, PRPF31, PRPF38A, PRPF38B, PRPF39, PRPF40A, PRPF40B)
RNA editing · Polyuridylation
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| Cytosolic |
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see also disorders of transcription and post transcriptional modification
B bsyn: dna (repl, cycl, reco, repr) · tscr (fact, tcrg, nucl, rnat, rept, ptts) · tltn (risu, pttl, nexn) · dnab, rnab/runp · stru (domn, 1°, 2°, 3°, 4°)
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| snRNP |
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| hnRNP |
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| Other transcription |
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| Translation |
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| Vault ribonucleoprotein particles |
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| Other |
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B bsyn: dna (repl, cycl, reco, repr) · tscr (fact, tcrg, nucl, rnat, rept, ptts) · tltn (risu, pttl, nexn) · dnab, rnab/runp · stru (domn, 1°, 2°, 3°, 4°)
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