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CAAT结构是一种在真核生物启动子中普遍存在的顺式作用元件.CBF,又称为NF-Y、CP1,是一个CAAT特异性转录因子.在转录过程中,CBF与CAAT特异性结合,共同调控启动子的转录,本文综述了CBF的结构及其在转录中的作用. 相似文献
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CAAT结构是一种在真核生物启动子中普遍存在的顺式作用元件。CBF,又称为NF -Y、CP1,是一个CAAT特异性转录因子。在转录过程中 ,CBF与CAAT特异性结合 ,共同调控启动子的转录 ,本文综述了CBF的结构及其在转录中的作用。1CAAT结构CAAT结构存在于由RNA聚合酶Ⅱ所转录的大多数真核生物基因的近端启动子中〔1〕,它与其他的启动子元件相互协调 ,一起控制启动子的转录活性。在高等的真核细胞启动子中 ,CAAT一般位于 -80区〔2〕。对不同物种的某些基因进行比较 ,发现CAAT结构在启动子上的位置以… 相似文献
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Role of the Adenovirus DNA-Binding Protein in In Vitro Adeno-Associated Virus DNA Replication 总被引:5,自引:5,他引:0
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Peter Ward Frank B. Dean Michael E. ODonnell Kenneth I. Berns 《Journal of virology》1998,72(1):420-427
A basic question in adeno-associated virus (AAV) biology has been whether adenovirus (Ad) infection provided any function which directly promoted replication of AAV DNA. Previously in vitro assays for AAV DNA replication, using linear duplex AAV DNA as the template, uninfected or Ad-infected HeLa cell extracts, and exogenous AAV Rep protein, demonstrated that Ad infection provides a direct helper effect for AAV DNA replication. It was shown that the nature of this helper effect was to increase the processivity of AAV DNA replication. Left unanswered was the question of whether this effect was the result of cellular factors whose activity was enhanced by Ad infection or was the result of direct participation of Ad proteins in AAV DNA replication. In this report, we show that in the in vitro assay, enhancement of processivity occurs with the addition of either the Ad DNA-binding protein (Ad-DBP) or the human single-stranded DNA-binding protein (replication protein A [RPA]). Clearly Ad-DBP is present after Ad infection but not before, whereas the cellular level of RPA is not apparently affected by Ad infection. However, we have not measured possible modifications of RPA which might occur after Ad infection and affect AAV DNA replication. When the substrate for replication was an AAV genome inserted into a plasmid vector, RPA was not an effective substitute for Ad-DBP. Extracts supplemented with Ad-DBP preferentially replicated AAV sequences rather than adjacent vector sequences; in contrast, extracts supplemented with RPA preferentially replicated vector sequences. 相似文献
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Transcription In Vitro by Reovirus-Associated Ribonucleic Acid-Dependent Polymerase 总被引:31,自引:23,他引:8
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Digestion of purified reovirus type 3 with chymotrypsin degrades 70% of the viral protein and converts the virions to subviral particles (SVP). The SVP contain 3 of the 6 viral structural proteins and all 10 double-stranded ribonucleic acid (RNA) genome segments but not adenine-rich, single-stranded RNA. An RNA polymerase which is structurally associated with SVP transcribes one strand of each genome segment by a conservative mechanism in vitro. The single-stranded products include large (1.2 x 10(6) daltons), medium (0.7 x 10(6) daltons), and small (0.4 x 10(6) daltons) molecules which hybridize exclusively with the corresponding genome segments. The enzyme obtained by heating virions at 60 C synthesizes similar products. Kinetic and pulse-chase studies indicate that the different-sized products are synthesized simultaneously but at rates which are in the order: small > medium > large. 相似文献
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采用逆转录聚合酶链反应(RT-PCR)从广东省一例慢性丙型肝炎病人血清中获得丙型肝炎病毒(HCV)5'端非编码区(5'NCR)302bp的cDNA片段,经补齐和提纯后插入pUC19质粒,获得的重组体pUN进行序列测定。将pUN的目的基因亚克隆进体外转录载体pSPORTI多克隆位点的EooRI和PstI切点之间,所得重组体pSN线性化后由T_7RNA多聚酶及SP6RNA多聚酶引导体外转录反应,产物经凝胶电泳及特异引物RT-PCR,证实SP6引导的是正义RNA,T7合成的是反义RNA,其大小分别力429bp和362bp。并证实所得RNA力HCV5'NCRcDNA转录而来。获得的HCV5'NCRcDNA和RNA在常规逆转录和PCR步骤中用于设立有效的模板对照,对消除假用性及评估试剂有重要意义。同时,HCV5'NCR体外转录载体的构建可用于制各RNA探针和反义RNA,改进后还可作为定量PCR的竞争性模板。 相似文献
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Nucleosomes and their positions in the eukaryotic genome play an important role in regulating gene expression by influencing accessibility to DNA. Many factors influence a nucleosome''s final position in the chromatin landscape including the underlying genomic sequence. One of the primary reasons for performing in vitro nucleosome reconstitution experiments is to identify how the underlying DNA sequence will influence a nucleosome''s position in the absence of other compounding cellular factors. However, concerns have been raised about the reproducibility of data generated from these kinds of experiments. Here we present data for in vitro nucleosome reconstitution experiments performed on linear plasmid DNA that demonstrate that, when coverage is deep enough, these reconstitution experiments are exquisitely reproducible and highly consistent. Our data also suggests that a coverage depth of 35X be maintained for maximal confidence when assaying nucleosome positions, but lower coverage levels may be generally sufficient. These coverage depth recommendations are sufficient in the experimental system and conditions used in this study, but may vary depending on the exact parameters used in other systems. 相似文献
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Most (if not all) SPP1 RNA can be synthesized in infected cells in the presence of chloramphenicol, or in vitro by Bacillus subtilis RNA polymerase. 相似文献