RNA splicing

Source: Wikipedia. Pages: 48. Chapters: RNA, Intron, Exon, Messenger RNA, Spliceosome, Alternative splicing, U7 small nuclear RNA, Hammerhead ribozyme, U4 spliceosomal RNA, RNase P, Group I catalytic intron, Hairpin ribozyme, SnRNP70, U6 spliceosomal RNA, Minor spliceosome, GIR1 branching ribozyme, Transcriptome, Group II intron, C1QL1, SmY RNA, Ligase ribozyme, Small Cajal body-specific RNA, Group III intron, Small Cajal body specific RNA 15, Small Cajal body specific RNA 18, Small Cajal body specific RNA 13, Small Cajal body specific RNA 6, U1 spliceosomal RNA, Hepatitis delta virus ribozyme, Small Cajal body specific RNA 21, Small Cajal body specific RNA 24, Small Cajal body specific RNA 20, U12 minor spliceosomal RNA, Small Cajal body specific RNA 23, Small nucleolar RNA SNORD67, Small Cajal body specific RNA 16, Twintron, Small Cajal body specific RNA 8, U4atac minor spliceosomal RNA, Trans-splicing, Small nucleolar RNA SNORA74, Small Cajal body specific RNA 11, Alternative splicing and transcript diversity database, Beta-globin co-transcriptional cleavage ribozyme, RNase MRP, U6atac minor spliceosomal RNA, Yeast U1 spliceosomal RNA, U2 spliceosomal RNA, U5 spliceosomal RNA, AspicDB, Human-transcriptome database for alternative splicing, SpliceInfo, Alternative splicing annotation project, DBASS3/5, ProSAS, Intronerator, Exon-intron database, ECgene, Hollywood, Fusion transcript, TassDB, Mammalian CPEB3 ribozyme, Leadzyme, U12 intron database, U11 spliceosomal RNA, EDAS, GISSD, VS ribozyme. Excerpt: Alternative splicing (or differential splicing) is a process by which the exons of the RNA produced by transcription of a gene (a primary gene transcript or pre-mRNA) are reconnected in multiple ways during RNA splicing. The resulting different mRNAs may be translated into different protein isoforms; thus, a single gene may code for multiple proteins. Alternative splicing occurs as a normal phenomenon in eukaryotes, where it greatly increases the diversity of proteins that can be encoded by the genome; in humans, ~95% of multiexonic genes are alternatively spliced. There are numerous modes of alternative splicing observed, of which the most common is exon skipping. In this mode, a particular exon may be included in mRNAs under some conditions or in particular tissues, and omitted from the mRNA in others. The production of alternatively spliced mRNAs is regulated by a system of trans-acting proteins that bind to cis-acting sites on the pre-mRNA itself. Such proteins include splicing activators that promote the usage of a particular splice site, and splicing repressors that reduce the usage of a particular site. Mechanisms of alternative splicing are highly variable, and new examples are constantly being found, particularly through the use of high-throughput techniques. Researchers hope to fully elucidate the regulatory systems involved in splicing, so that alternative splicing products from a given gene under particular conditions could be predicted by a "splicing code". Abnormal variations in splicing are also implicated in disease; a large proportion of human genetic disorders result from splicing variants. Abnormal splicing variants are also thought to contribute to the development of cancer, although such aberrant splicing products are, under normal conditions, usually safeguarded and eliminated by a posttranscriptional quality control mechanism. Alternative splicing was first observed in 1977. Adenoviruses produce two different prim...