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In Schizosaccharomyces pombe, interdependency in rRNA processing is mediated by a large protein complex (RAC) which contains independent binding sites for each of the transcribed spacers. The RAC complex exhibits no nuclease activity but dramatically alters the efficiency and specificity of the Pac1 nuclease, leading to the complete removal of the 3' ETS. Furthermore, the affinity of RAC protein for mutant 3' ETS correlates closely with in vivo effects on rRNA processing, and changes which disrupt RAC protein binding also inhibit Pac1 nuclease cleavage at the 3' end of the 25S rRNA sequence. The observations indicate that, in the presence of the RAC protein/3' ETS complex, cleavage by the RNase III-like homolog is not restricted to the known intermediate sites but also is directed at the 3' end of the 25S rRNA. 相似文献
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Morphogen gradient formation and vesicular trafficking 总被引:3,自引:1,他引:2
Morphogens are secreted signaling molecules which form spatial concentration gradients while moving away from a restricted source of production. A simple model of gradient formation postulates that the morphogens dilute as they diffuse between cells. In this review we discuss recent data supporting the idea that movement of the morphogen could also occur via vesicular trafficking through the cells. We explore the implications of these results for the control of gradient formation and the determination of the gradient slope which ultimately encodes the coordinates of positional information. 相似文献
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Multiplexed genotyping with sequence-tagged molecular inversion probes 总被引:19,自引:0,他引:19
Hardenbol P Banér J Jain M Nilsson M Namsaraev EA Karlin-Neumann GA Fakhrai-Rad H Ronaghi M Willis TD Landegren U Davis RW 《Nature biotechnology》2003,21(6):673-678
We report on the development of molecular inversion probe (MIP) genotyping, an efficient technology for large-scale single nucleotide polymorphism (SNP) analysis. This technique uses MIPs to produce inverted sequences, which undergo a unimolecular rearrangement and are then amplified by PCR using common primers and analyzed using universal sequence tag DNA microarrays, resulting in highly specific genotyping. With this technology, multiplex analysis of more than 1,000 probes in a single tube can be done using standard laboratory equipment. Genotypes are generated with a high call rate (95%) and high accuracy (>99%) as determined by independent sequencing. 相似文献
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Alexey Fedorov Larisa Fedorova Valery Starshenko Vadim Filatov Eugeni Grigor'ev 《Journal of molecular evolution》1998,46(3):263-271
Nonrandomness in the intron and exon phase distributions in a sample of 305 human genes has been found and analyzed. It was
shown that exon duplications had a significant effect on the exon phase nonrandomness. All of the nonrandomness is probably
due to both the processes of exon duplication and shuffling. A quantitative estimation of exon duplications in the human genome
and their influence on the intron and exon phase distributions has been analyzed. According to our estimation, the proportion
of duplicated exons in the human genome constitutes at least 6% of the total. Generalizing the particular case of exon duplication
to the more common event of exon shuffling, we modeled and analyzed the influence of exon shuffling on intron phase distribution.
Received: 28 March 1997 / Accepted: 9 July 1997 相似文献
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G protein-coupled receptors (GPCRs) are seven-transmembrane-spanning proteins that mediate cellular and physiological responses. They are critical for cardiovascular function and are targeted for the treatment of hypertension and heart failure. Nevertheless, current therapies only target a small fraction of the cardiac GPCR repertoire, indicating that there are many opportunities to investigate unappreciated aspects of heart biology. Here, we offer an update on the contemporary view of GPCRs and the complexities of their signalling, and review the roles of the ‘classical’ GPCRs in cardiovascular physiology and disease. We then provide insights into other GPCRs that have been less extensively studied in the heart, including orphan, odorant and taste receptors. We contend that these novel cardiac GPCRs contribute to heart function in health and disease and thereby offer exciting opportunities to therapeutically modulate heart function. 相似文献
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Cristina Oliveras-Ferraros Alejandro Vazquez-Martin Begoña Martin-Castillo Silvia Cufí Sonia Del Barco Eugeni Lopez-Bonet Javier A. Menendez 《Biochemical and biophysical research communications》2010,397(1):27-1021
Evidence is mounting that the occurrence of the CD44pos/CD24neg/low cell population, which contains potential breast cancer (BC) stem cells, could explain BC clinical resistance to HER2-targeted therapies. We investigated whether de novo refractoriness to the anti-HER2 monoclonal antibody trastuzumab (Tzb; Herceptin) may relate to the dynamic regulation of the mesenchymal CD44pos/CD24neg/low phenotype in HER2-positive BC. We observed that the subpopulation of Tzb-refractory JIMT-1 BC cells exhibiting CD44pos/CD24neg/low-surface markers switched with time. Low-passage JIMT-1 cell cultures were found to spontaneously contain ∼10% of cells bearing the CD44pos/CD24neg/low immunophenotype. Late-passage (>60) JIMT-1 cultures accumulated ∼80% of CD44pos/CD24neg/low cells and closely resembled the CD44pos/CD24neg/low-enriched (∼85%) cell population constitutively occurring in HER2-negative MDA-MB-231 mesenchymal BC cells. Dynamic expression of mesenchymal markers was not limited to CD44/CD24 because high-passages of JIMT-1 cells exhibited also reduced expression of the HER2 protein and over-secretion of pro-invasive/metastatic chemokines and metalloproteases. Accordingly, late-passage JIMT-1 cells displayed an exacerbated migratogenic phenotype in plastic, collagen, and fibronectin substrates. Intrinsic genetic plasticity to efficiently drive the emergence of the CD44pos/CD24neg/low mesenchymal phenotype may account for de novo resistance to HER2 targeting therapies in basal-like BC carrying HER2 gene amplification. 相似文献