Small nuclear ribonucleoprotein particles snRNPs

To assist in the modification and processing of mRNAs, eukaryotic cells contain in their nuclei small nuclear RNAs (snRNAs), which are complexed with specific proteins to form small nuclear ribonucleoprotein particles (snRNPs). These RNAs have been named U1, U2, U3,.. . , U13 and range in size from 100 to 220 bases. One, U3, is... 

The small nuclear ribonucleoprotein particles (snRNPs or snurps ) that carry out the splicing reaction use RNA-RNA basepairing to select the splice sites. Almost all intron-exon junctions contain the sequence AG-GU with the GU beginning the intron sequence. Furthermore, the consensus sequence for the beginning of the intron has a longer sequence complementary to the U1 RNA. Thus, assembly of the splicing complex, called the spliceosome, starts when the RNA component of the U1 snRNP base pairs with the junction between the 3 end of the exon and the 5 end of the intron. See Figure 12-13. 

Table 11.4 Small Nuclear Ribonucleoprotein Particles (snRNP) in Splicing of mRNA Precursors...

Table 28.3. Small nuclear ribonucleoprotein particles (snRNPs) in the splicing of mRNA precursors...

The splicing of mRNA precursors is carried out by spliceosomes, which consist of small nuclear ribonucleoprotein particles (snRNPs). Splice sites in mRNA precursors are specified by sequences at ends of introns and by branch sites... 

Most striking is the splicing of mRNA precursors, which is catalyzed by spliceosomes consisting of small nuclear ribonucleoprotein particles (snRNPs). The small nuclear RNA (snRNA) molecules in these complexes play a key role in directing the alignment of splice sites and in mediating catalysis. Indeed, some RNA molecules can splice themselves in the absence of protein. This landmark discovery by Thomas Cech and Sidney Altman revealed that RNA molecules can serve as catalysts and greatly influenced our view of molecular evolution. 

Small nuclear RNA (snRNA) molecules form part of the spliceosome that is involved in cleaving introns out of mRNA precursors. There are five of these special suRNAs, called U1, U2, U4, U5, and U6. They range in size from 50 to 200 nucleotides and form complexes with proteins to form small nuclear ribonucleoprotein particles (snRNPs). 

Removal of introns. snRNP = small nuclear ribonucleoprotein particle. 

D, Keller W. Functions of the abundant U-snRNPs. In Small Nuclear Ribonucleoprotein Particles. Birnstiel ML, ed. 1988. Springer-Verlag, Berlin. 53. 

Luhrmann, R. (1988) snRNP proteins. In Small Nuclear Ribonucleoprotein Particles (ed. Birnstiel, M. L.) Springer-Verlag, pp. 71-99. 

Small nuclear RNA (snRNA) is found in the eukaryotic nucleus and is involved in splicing reactions of other RNA types. An snRNP is a small nuclear ribonucleoprotein particle. A complex of small nuclear RNA and protein catalyzes splicing of RNA. 

The snRNPs are small nuclear ribonucleoprotein particles. They are the site of mRNA splicing. 

Splicing takes place in a 50-60S small nuclear ribonucleoprotein (snRNP) particle called spliceosome consisting of a pre-mRNA, small nuclear RNAs (snRNAs) and a variety of pre-mRNA binding proteins, which ensures the proper excision of all introns and precise splicing of exons. 

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