Benutzer:Tronicum/sandbox/SmY
SmY RNAs sind eine Gruppe small nuclear RNAs die in Nematoden entdeckt wurden. Es wird vermutet, dass sie im Prozess des Transspleißen von Boten RNS eine Rolle spielen weil they copurify with spliceosomes and with some of the same proteins that associate with small ribonucleoprotein particles containing SL1 and SL2 trans-spliced leader RNAs.[1] [2]
Function
The first SmY RNA was discovered in purified Ascaris lumbricoides spliceosome preparations, as well as a second RNA called SmX that is not detectably homologous to SmY.[1] Twelve SmY homologs were identified computationally in Caenorhabditis elegans, and ten in Caenorhabditis briggsae.[2] Several transcripts from these SmY genes were cloned and sequenced in a systematic survey of small noncoding RNA transcripts in C. elegans.[3] SmY RNAs are about 70-90 nucleotides long, with a conserved consensus binding site for the Sm protein, a shared component of spliceosomal snRNPs.[1][2] In C. elegans, SmY RNAs copurify in a complex with Sm, SL75p, and SL26p proteins, while the better-characterized C. elegans SL1 trans-splicing snRNA copurifies in a complex with Sm, SL75p and SL21p (a paralog of SL26p).[2] Loss of function of either SL21p or SL26p individually causes only a weak cold-sensitive phenotype, whereas knockdown of both is lethal, as is a SL75p knockdown. Based on these results, the SmY RNAs are believed to have a function in trans-splicing.
Structure
SmY RNAs conserve a consensus secondary structure with two stem-loops, flanking a consensus Sm protein binding site.
Phylogenetic range
SmY RNAs have been found in nematodes of class Chromadorea, which includes the most commonly studied nematodes (such as Caenorhabditis, Pristionchus, and Ascaris), but not in the more distantly related Trichinella spiralis in class Dorylaimia. The number of SmY genes in each species varies, with most Rhabditid species having 10-30 paralogous copies, while other nematodes have 1-5.
References
- ↑ a b c Maroney PA, Yu YT, Jankowska M, Nilsen TW: Direct analysis of nematode cis- and trans-spliceosomes: a functional role for U5 snRNA in spliced leader addition trans-splicing and the identification of novel Sm snRNPs. In: RNA. 2, Nr. 8, August 1996, S. 735-745. PMID 8752084. PMC 1369411 (freier Volltext).
- ↑ a b c d MacMorris M, Kumar M, Lasda E, Larsen A, Kraemer B, Blumenthal T: A novel family of C. elegans snRNPs contains proteins associated with trans-splicing. In: RNA. 13, Nr. 4, April 2007, S. 511-520. doi:10.1261/rna.426707. PMID 17283210. PMC 1831854 (freier Volltext).
- ↑ Deng W, Zhu X, Skogerbø G, et al: Organization of the Caenorhabditis elegans small non-coding transcriptome: genomic features, biogenesis, and expression. In: Genome Research. 16, Nr. 1, Januar 2006, S. 20-29. doi:10.1101/gr.4139206. PMID 16344563. PMC 1356125 (freier Volltext).
