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【答案】应助回帖
★ ★ ★ ★ ★ ★ ★ eiieen: 金币+2 2013-06-26 08:58:56 eiieen: 金币+3 2013-06-26 09:04:47 gyesang: 金币+2, 鼓励回帖应助! 2013-06-26 12:38:35
你就是这样提问的吗!?intronic splicing enhancer,exonic splicing enhancer的全称都不能明确写出吗!?
我现在知道intronic splicing enhancer,exonic splicing enhancer是分别在于一些intron和exon上的enhancer,有些特定的反式因子与其结合,按照一般的enhancer的作用机理(成环假说、扭曲假说、滑动假说和Oozing假说)影响可变剪接过程。
“Positive-acting splicing regulatory sequences generally can be classified by their location in either exons or introns. Exonic splicing enhancers are sequences, found in certain exons, that can stimulate spliceosome assembly at the upstream 3' splice site of the exon (Fu et al. 1991; Lavigueur et al. 1993; Sun et al. 1993; Watakabe et al. 1993; Caputi et al. 1994; Dirksen et al. 1994; Staknis and Reed 1994; Tanaka et al. 1994; Tian and Maniatis 1994; Ramchatesingh et al. 1995; Wang et al. 1995). Exonic enhancers are usually purine-rich sequences whose ac- ivity is mediated, at least in part, by a group of molecules known as SR (serine- and arginine-rich) proteins. These are a large family of proteins, found in both Drosophila and mammalian cells, each containing a serine- and arginine-rich domain and one or more RNA-binding domains of the ribonucleoprotein or RNP-type (Fu 1995; Manley and Tacke 1996; Valc~ircel and Green 1996). SR proteins have been implicated in many aspects of the splicing process. Most notably, they have been shown to bind to exonic enhancers and in one case to synergize with more specialized regulatory proteins bound to the enhancer (Lynch and Maniatis
1996). Although less understood than exonic splicing enhancers, there are also intronic sequences that activate splicing (Balvay et al. 1992; Black 1992; Huh and Hynes 1994; Del Gatto and Breathnach 1995; Lou et al. 1995; Sirand-Pugnet et al. 1995; Carlo et al. 1996; Ryan and Cooper 1996). Intronic splicing enhancers are often found in the introns downstream of regulated exons and are required for the splicing of these exons. They have been identified in an array of transcripts, including c-src, fibronectin, ~-tropomyosin, fibroblast growth factor re-
ceptor, cardiac troponin T, and calcitonin/calcitonin gene-related peptide. These intronic enhancers contain diverse sequence elements that are often repeated and
show a variety of tissue specific regulation. So far, SR proteins have not been found to bind to these sequences. Although the c-src intronic enhancer binds to a complex of proteins, including the heterogeneous nuclear ribonucleoprotein F (hnRNP F), other proteins that mediate splicing through these regulatory sequences are unknown (Min et al. 1995). ”------From :Hosung Min, Christoph W. Turck, Julia M. Nikolic, and Douglas L. Black ,A new regulatory protein, KSRP, mediates exon inclusion through an intronic splicing enhancer,GENES & DEVELOPMENT 1997,11:1023-1036. |
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