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  • exon
  • Several types of different alternative splice forms exist including exon skipping, differential splicing of exons at their 3'- or 5'-end, intron retention, and mutually exclusive splicing. (biomedcentral.com)
  • The first type is exon skipping, in which an exon, also called cassette exon, is spliced out of the transcript together with its flanking introns. (biomedcentral.com)
  • The fourth type is intron retention in which part of an exon is either spliced (like a regular intron) or retained in the mature mRNA transcript. (biomedcentral.com)
  • splice
  • Then, within the cell nucleus, specialized arrays of enzymes in complexes called spliceosomes locate the introns, snip them out, and splice the RNA back together. (panspermia.org)
  • Group II introns are further sub-classified into groups IIA and IIB, which differ in splice site consensus, and the distance of the bulged adenosine in domain VI (the prospective branch point forming the lariat) from the 3' splice site. (wikipedia.org)
  • These U12-dependent introns are under-represented in genome annotations because they often have non canonical splice sites. (wikipedia.org)
  • The secondary structure of the HAC1/XBP1 intron is very well conserved, and consists of two hairpins (H2 and H3) around the splice sites, and an extended hairpin (H1) that brings the splice sites together (see figure). (wikipedia.org)
  • move the intron
  • Further experiments can specifically point to IME as the cause of expression enhancement - one of the most common is to move the intron upstream of the transcription start site, removing it from the transcript. (wikipedia.org)
  • Yeast
  • Mining existing data from genomewide studies on yeast revealed that intron-containing genes produce more RNA and more protein and are more likely to be haplo-insufficient than nonintronic genes. (genetics.org)
  • These data provide evidence that introns improve transcriptional and translational yield and are required for competitive growth of yeast. (genetics.org)
  • We further show that genetic deletion of introns from yeast genes decreases mRNA production, and in two cases of three we show that intron removal causes a phenotypic growth defect. (genetics.org)
  • We conclude from these observations that introns confer fitness to an organism by improving transcriptional and translational output and suggest that they are required for competitive growth of yeast in their natural environment. (genetics.org)
  • cerevisiae
  • To assay the functional relevance of introns, a series of computational analyses and several detailed deletion studies were completed on the intronic genes of S. cerevisiae . (genetics.org)
  • To investigate the role that introns may play in cellular fitness we studied their genetic contribution to the fitness of Saccharomyces cerevisiae . (genetics.org)
  • It could be interpreted that the introns in S. cerevisiae are nucleic acid relics that have yet to be removed by evolution ( F ink 1987 ). (genetics.org)
  • In Saccharomyces cerevisiae the long intron pairs with the 5' UTR and stalls the ribosomes on the mRNA. (wikipedia.org)
  • nucleotide
  • Intron position was defined at the nucleotide level making it possible to determine whether the intron is at an identical position (same codon and same phase) or not in the homologues. (gsf.de)
  • peginterferon
  • Peg-Intron (peginterferon alfa-2b) Powder for Injection has been approved by the FDA as a once-weekly monotherapy for the treatment of chronic hepatitis C. It is indicated for patients with compensated liver disease who were not previously treated with alpha interferon. (centerwatch.com)
  • Peginterferon (PEG-INTRON, Schering Corporation, Kenilworth, NJ) is a new formulation of interferon recently approved for the treatment of HCV. (pharmacytimes.com)
  • gene expression
  • The question arises: Are the introns directly responsible for increasing gene expression or does their removal act indirectly, by simply derailing the mRNA synthesis assembly line? (genetics.org)
  • There is, however, no consensus that introns serve to increase gene expression. (genetics.org)
  • Not all introns enhance gene expression, but those that do can enhance expression between 2- and >1,000-fold relative to an intronless control. (wikipedia.org)
  • The position of an intron within the transcript is also important - the closer an intron is to the start (5' end) of a transcript, the greater its enhancement of gene expression. (wikipedia.org)
  • The small T intron is an intron that is used in some plasmid vectors in order to induce gene expression in mammalian cells. (wikipedia.org)
  • upstream
  • MCM6 contains two of the regulatory regions for LCT, the gene encoding the protein lactase, located in two of the MCM6 introns, approximately 14 kb (-13910) and 22 kb (-22018) upstream of LCT. (wikipedia.org)
  • 1977
  • The fact that genes were split or interrupted by introns was discovered independently in 1977 by Phillip Allen Sharp and Richard J. Roberts , for which they shared the Nobel Prize in Physiology or Medicine in 1993. (wikipedia.org)
  • A surprising phenomenon was discovered in 1977 - introns. (panspermia.org)
  • Soundsystem
  • Introns is an album by LCD Soundsystem released in March 2006 as a digital download . (wn.com)
  • For the interferon-based drug used in viral and cancer treatments, see Intron A . For the album by LCD Soundsystem , see Introns (album) . (wikipedia.org)
  • Introns is a remix album by the American rock band LCD Soundsystem, released in March 2006 through DFA as a digital download. (wikipedia.org)
  • transcript
  • The preponderance of retained introns (65%) were either part of open reading frames, present in the UTR region or present as the last intron in the transcript, indicating that their occurrence would not participate in non-sense-mediated decay. (futura-sciences.com)
  • If the intron can no longer enhance expression, then inclusion of the intron in the transcript is important, and the intron probably causes IME. (wikipedia.org)
  • expression of a gene
  • When testing to see whether any given intron enhances the expression of a gene, it is typical to compare the expression of two constructs, one containing the intron and one without it, and to express the difference between the two results as a "fold increase" in enhancement. (wikipedia.org)
  • 1990
  • Descriptions of this phenomenon were first published in cultured maize cells in 1987, and the term "intron-mediated enhancement" was subsequently coined in 1990. (wikipedia.org)
  • transcription
  • Following transcription into RNA, group I and group II introns also make extensive internal interactions that allow them to fold into a specific, complex three-dimensional architecture. (wikipedia.org)
  • homologues
  • CLUSTALX multiple alignments were performed to verify the degree of conservation of the homologues and to reconstruct a virtual (scaffold) gene, exhibiting the probable ancestral intron arrangement. (gsf.de)
  • Arabidopsis
  • Search algorithms of AS forms in a variety of Arabidopsis databases showed they contained an unusually high fraction of retained introns (above 30%), compared with 10%that was reported for humans. (futura-sciences.com)
  • Thus, retained introns are a prominent feature of AS in Arabidopsis and as such may play a regulatory function. (futura-sciences.com)
  • selfish
  • For Richard Dawkins, introns are an example of pure "selfish DNA," out for its own survival only. (panspermia.org)
  • It is unclear whether introns serve some specific function, or whether they are selfish DNA which reproduces itself as a parasite . (wikipedia.org)
  • occurs
  • Although it is now admitted that intron sliding by one or two bases is a real phenomenon, it remains relatively rare and probably occurs in less than 5% of all introns [Stoltzfus et al. (gsf.de)
  • transcripts
  • Interestingly, the functional distribution of the transcripts with retained introns is skewed towards stress and external/internal stimuli-related functions. (futura-sciences.com)
  • A sampling of the alternative transcripts with retained introns were confirmed by RT-PCR and were shown to co-purify with polyribosomes, indicating their nuclear export. (futura-sciences.com)
  • Mechanism
  • Two-metal-ion mechanism seen in protein polymerases and phosphatases was proposed to be used by group I and group II introns to process the phosphoryl transfer reactions, which was unambiguously proven by a recently resolved high-resolution structure of the Azoarcus group I intron. (wikipedia.org)
  • poly A ta
  • I am assuming that the question wants us to draw an organization that has not yet been spliced, so I included the introns and also the G-cap and poly A tail. (biology-online.org)