966 resultados para SUBUNIT MESSENGER-RNAS
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Mutations in the gene encoding the beta subunit of rod cGMP phosphodiesterase are known causes of photoreceptor degeneration in two animal models of retinitis pigmentosa, the rd (retinal degeneration) mouse and the Irish setter dog with rod/cone dysplasia. Here we report a screen of 92 unrelated patients with autosomal recessive retinitis pigmentosa for defects in the human homologue of this gene. We identified seven different mutations that cosegregate with the disease. They were found among four patients with each patient heterozygously carrying two mutations. All of these mutations are predicted to affect the putative catalytic domain, probably leading to a decrease in phosphodiesterase activity and an increase in cGMP levels within rod photoreceptors. Mutations in the gene encoding the beta subunit of rod phosphodiesterase are the most common identified cause of autosomal recessive retinitis pigmentosa, accounting for approximately 4% of cases in North America.
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The human general transcription factor TFIIA is one of several factors involved in specific transcription by RNA polymerase II, possibly by regulating the activity of the TATA-binding subunit (TBP) of TFIID. TFIIA purified from HeLa extracts consists of 35-, 19-, and 12-kDa subunits. Here we describe the isolation of a cDNA clone (hTFIIA gamma) encoding the 12-kDa subunit. Using expression constructs derived from hTFIIA gamma and TFIIA alpha/beta (which encodes a 55-kDa precursor to the alpha and beta subunits of natural TFIIA), we have constructed a synthetic TFIIA with a polypeptide composition similar to that of natural TFIIA. The recombinant complex supports the formation of a DNA-TBP-TFIIA complex and mediates both basal and Gal4-VP16-activated transcription by RNA polymerase II in TFIIA-depleted nuclear extracts. In contrast, TFIIA has no effect on tRNA and 5S RNA transcription by RNA polymerase III in this system. We also present evidence that both the p55 and p12 recombinant subunits interact with TBP and that the basic region of TBP is critical for the TFIIA-dependent function of TBP in nuclear extracts.
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Cohesin's Smc1, Smc3, and kleisin subunits create a tripartite ring within which sister DNAs are entrapped. Evidence suggests that DNA enters through a gate created by transient dissociation of the Smc1/3 interface. Release at the onset of anaphase is triggered by proteolytic cleavage of kleisin. Less well understood is the mechanism of release at other stages of the cell cycle, in particular during prophase when most cohesin dissociates from chromosome arms in a process dependent on the regulatory subunit Wapl. We show here that Wapl-dependent release from salivary gland polytene chromosomes during interphase and from neuroblast chromosome arms during prophase is blocked by translational fusion of Smc3's C-terminus to kleisin's N-terminus. Our findings imply that proteolysis-independent release of cohesin from chromatin is mediated by Wapl-dependent escape of DNAs through a gate created by transient dissociation of the Smc3/kleisin interface. Thus, cohesin's DNA entry and exit gates are distinct.
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Circulating miRNAs in body fluids, particularly serum, are promising candidates for future routine biomarker profiling in various pathologic conditions in human and veterinary medicine. However, reliable standardized methods for miRNA extraction from equine serum and fresh or archived whole blood are sorely lacking. We systematically compared various miRNA extraction methods from serum and whole blood after short and long-term storage without addition of RNA stabilizing additives prior to freezing. Time of storage at room temperature prior to freezing did not affect miRNA quality in serum. Furthermore, we showed that miRNA of NGS-sufficient quality can be recovered from blood samples after >10 years of storage at -80 °C. This allows retrospective analyses of miRNAs from archived samples.
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As translation is the final step in gene expression it is particularly important to understand the processes involved in translation regulation. It was shown in the last years that a class of RNA, the nonprotein-coding RNAs (ncRNAs), is involved in regulation of gene expression via various mechanisms (e.g. gene silencing by microRNAs). Almost all of these ncRNA discovered so far target the mRNA in order to modulate protein biosynthesis, this is rather unexpected considering the crucial role of the ribosome during gene expression. However, recent data from our laboratory showed that there is a new class of ncRNAs, which target the ribosome itself [Gebetsberger et al., 2012/ Pircher et al, 2014]. These so called ribosome-associated ncRNAs (rancRNAs) have an impact on translation regulation, mainly by interfering / modulating the rate of protein biosynthesis. The main goal of this project is to identify and describe novel potential regulatory rancRNAs in H. volcanii with the focus on intergenic candidates. Northern blot analyses already revealed interactions with the ribosome and showed differential expression of rancRNAs during different growth phases or under specific stress conditions. To investigate the biological relevance of these rancRNAs, knock-outs were generated in H. volcanii which were used for phenotypic characterization studies. The rancRNA s194 showed association with the 50S ribosomal subunit in vitro and in vivo and was capable of inhibiting peptide bond formation. These preliminary data for the rancRNA s194 make it an interesting candidate for further functional studies to identify the molecular mechanisms by which rancRNAs can modulate protein biosynthesis. Characterization of further rancRNA candidates are also underway.
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Vol. 1, no. 7 and no. 8 are paginated so that v. 1, no. 8 comes before v. 1, no. 7.
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Mode of access: Internet.
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Publication suspended, 1895-1899.
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Mode of access: Internet.
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Mode of access: Internet.
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Mode of access: Internet.
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Published: Buffalo [N.Y.] : Thomas & Lathrop, Sept. 1854-
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Editors: Nov. 1837-Oct. 1839, J.F. Clarke (May-Oct. 1839 assisted by W.H. Channing and J.H. Perkins.
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Mode of access: Internet.
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None published: 1954-1955.