共查询到20条相似文献，搜索用时 109 毫秒
1.
Cyclic cytidine 2',3'-phosphate: molecular structure 总被引：1，自引：0，他引：1
Monoclinic crystals of the sodium salt of cytidine 2',3'-phosphate contain two anions in the asymmetric unit. Both bases are in the syn conformation, and the nucleotides are stacked together into an antiparallel stranded ribbon with the bases 3.3 angstroms apart. One ribose ring is planar, and the other has oxygen-1' puckered toward carbon-5'. The phosphorus atoms in the five-membered ester rings are puckered toward the sugars. The conformations about the carbon-4'-carbon-5' bonds are gauche-trans and gauche-gauche. 相似文献
2.
3.
A subline of U937 cells (U937D) was obtained in which creatine kinase B (CK-B) messenger RNA was present and bound to ribosomes, but CK activity was undetectable. Transformation of U937D cells with retrovirus vectors that contain the 3' untranslated region (3' UTR) of CK-B messenger RNA exhibited CK activity with no change in abundance of CK-B mRNA. The 3' UTR formed a complex in vitro with a component of S100 extracts from wild-type cells. This binding activity was not detectable in S100 extracts from cells that expressed CK activity after transformation with the 3' UTR-containing vector. These results suggest that translation of CK-B is repressed by binding of a soluble factor or factors to the 3' UTR. 相似文献
4.
Specific interactions in RNA enzyme-substrate complexes 总被引：27，自引：0，他引：27
Analysis of crosslinked complexes of M1 RNA, the catalytic RNA subunit of ribonuclease P from Escherichia coli, and transfer RNA precursor substrates has led to the identification of regions in the enzyme and in the substrate that are in close physical proximity to each other. The nucleotide in M1 RNA, residue C92, which participates in a crosslink with the substrate was deleted and the resulting mutant M1 RNA was shown to cleave substrates lacking the 3' terminal CCAUCA sequence at sites several nucleotides away from the normal site of cleavage. The presence or absence of the 3' terminal CCAUCA sequence in transfer RNA precursor substrates markedly affects the way in which these substrates interact with the catalytic RNA in the enzyme-substrate complex. The contacts between wild-type M1 RNA and its substrate are in a region that resembles part of the transfer RNA "E" (exit) site in 23S ribosomal RNA. These data demonstrate that in RNA's with very different cellular functions, there are domains with similar structural and functional properties and that there is a nucleotide in M1 RNA that affects the site of cleavage by the enzyme. 相似文献
5.
Antisense RNA directed against the 3' noncoding region prevents dormant mRNA activation in mouse oocytes 总被引：22，自引：0，他引：22
S Strickland J Huarte D Belin A Vassalli R J Rickles J D Vassalli 《Science (New York, N.Y.)》1988,241(4866):680-684
Primary mouse oocytes contain untranslated stable messenger RNA for tissue plasminogen activator (t-PA). During meiotic maturation, this maternal mRNA undergoes a 3'-polyadenylation, is translated, and is degraded. Injections of maturing oocytes with different antisense RNA's complementary to both coding and noncoding portions of t-PA mRNA all selectively blocked t-PA synthesis. RNA blot analysis of t-PA mRNA in injected, matured oocytes suggested a cleavage of the RNA.RNA hybrid region, yielding a stable 5' portion, and an unstable 3' portion. In primary oocytes, the 3' noncoding region was susceptible to cleavage, while the other portions of the mRNA were blocked from hybrid formation until maturation occurred. Injection of antisense RNA complementary to 103 nucleotides of its extreme 3' untranslated region was sufficient to prevent the polyadenylation, translational activation, and destabilization of t-PA mRNA. These results demonstrate a critical role for the 3' noncoding region of a dormant mRNA in its translational recruitment during meiotic maturation of mouse oocytes. 相似文献
6.
The type of RNA editing found in the kinetoplast-mitochondria of trypanosomes and related protozoa, involving uridylate insertions and deletions, creates translatable messenger RNAs (mRNAs) out of nonsense pre-edited RNAs by correcting encoded defects that vary from simple frameshifts to large "cryptic" regions. However, any evidence for translation of these mRNAs in the kinetoplast has been missing for decades. We identified a kinetoplast-encoded protein, apocytochrome b, whose mRNA is edited in the 5' region. The determined amino-terminal sequence of the protein coincides with the predicted sequence derived from the edited region, demonstrating that the cognate apocytochrome b mRNA is translated into a functional protein. This finding represents the first direct evidence for a functional translation system in the kinetoplasts. 相似文献
7.
[Objective] The aim of the study is to done the 5' flanking region of Sporamin A gene from sweet potato. [Method] The sweet potato "Xushu 18" was used to amplify the 5' flanking region of Sporamin A gene using specifically designed primers and then target fragment was analyzed by PLACE and PlantCare online. [Result] Besides the conserved elements including TATA-box and CAAT-box, the cis-acting elements including sucrose re- sponsive element CMSREI, SP8 acting site and some other regulatory sequence such as MTB binding site were also found in Spo A promoter sequence. The results suggest that the promoter has sucrose responsive function. [Conclusion] The study provided reference to reveal the regulation law of Spo A, and to develop high-level expression vectors promoted by Spo A promoter. 相似文献
8.
Translation in mammalian cells of a gene linked to the poliovirus 5' noncoding region 总被引：21，自引：0，他引：21
The central portion (region P) of the 742-nucleotide noncoding 5' end of poliovirus allows the RNA to initiate protein synthesis in the absence of the usual 5' 7-methylguanosine capping group. Poliovirus 5' noncoding region was fused to a reporter gene and transfected into cells. There was extensive augmentation of the expression of this gene by poliovirus-mediated inhibition of cap-dependent protein synthesis. That the construct initiated in a cap-independent manner was verified through in vitro experiments. Small lesions throughout region P blocked its initiation function, implying that a coherent functional unit, hundreds of nucleotides long, is responsible for cap-independent initiation by poliovirus RNA. 相似文献
9.
U1-specific protein C needed for efficient complex formation of U1 snRNP with a 5' splice site 总被引：18，自引：0，他引：18
One of the functions of U1 small nuclear ribonucleoprotein (snRNP) in the splicing reaction of pre-mRNA molecules is the recognition of the 5' splice site. U1 snRNP proteins as well as base-pair interactions between U1 snRNA and the 5' splice site are important for the formation of the snRNP-pre-mRNA complex. To determine which proteins are needed for complex formation, the ability of U1 snRNPs gradually depleted of the U1-specific proteins C, A, and 70k to bind to an RNA molecule containing a 5' splice site sequence was studied in a nitrocellulose filter binding assay. The most significant effect was always observed when protein C was removed, either alone or together with other U1-specific proteins; the binding was reduced by 50 to 60%. Complementation of protein C-deficient U1 snRNPs with purified C protein restored their 5' splice site binding activity. These data suggest that protein C may potentiate the base-pair interaction between U1 RNA and the 5' splice site. 相似文献
10.
11.
杂交豆2号选育及高产制种技术研究 总被引：9，自引：1，他引：9
杂交豆2号是利用"三系"法选育的大豆杂交种,不育系为JLCMS47A,恢复系为JLR2。杂交豆2号的主要特点是高产、稳产,品质较好,抗病性强。两年区试平均比对照增产22.7%,生产试验比对照增产14.3%。人工接种鉴定中抗大豆花叶病毒病和大豆灰斑病,田间自然诱发鉴定,对大豆花叶病毒病免疫、抗大豆灰斑病、抗大豆霜霉病、抗细菌性斑点病。子粒脂肪含量20.54%,蛋白质含量40.75%。杂交豆2号制种必须选择干旱少雨、有灌溉条件和天然昆虫群体多的地区进行。父母本错期播种,种植比例为1∶1或1∶2,密度为15～18万株/hm2。利用切叶蜂进行传粉,整个生育期严格去杂去劣,确保种子纯度。 相似文献
12.
13.
Adenosine 3',5'-monophosphate: regional differences in chick embryos at the head process stage 总被引：1，自引：0，他引：1
The concentrations of adenosine 3',5'-monophosphate and adenosine triphosphate and the activity of phosphodiesterase were determined in different regions of chick embryos at the head process stage. Adenosine 3',5'-monophosphate, adenosine triphosphate, and phosphodiesterase were estimated to be higher in the mesoderm-forming portions of the hypoblast than in portions that form neural structures from Hensen's node or the epiblast. 相似文献
14.
15.
16.
法尼基焦磷酸合酶是异戊二烯生物合成途径中的一个关键酶,根据NCBI数据库中巴西橡胶树法尼基焦磷酸合酶基因HbFPS序列设计引物,克隆了HbFPS起始密码子上游1066bp的5'调控序列。序列分析表明,该序列A/T含量为77.39%,含有典型的真核生物核心启动子区域,在该序列中发现了一些与真核生物典型的顺式调控元件相似的TATA-box、增强子元件、CAAT-box和GATA-box以及一些与激素、胁迫诱导、转录因子相关的顺式作用元件。构建了含有该序列的植物表达载体并转化烟草,对获得的转基因烟草T0代植株GUS染色发现转基因植株呈现蓝色,表明HbFPS的5'调控序列可以驱动GUS基因的表达,具有启动子的活性。 相似文献
17.
Expression of the 3' terminal region of human T-cell leukemia viruses 总被引：19，自引：0，他引：19
W Wachsman K Shimotohno S C Clark D W Golde I S Chen 《Science (New York, N.Y.)》1984,226(4671):177-179
Human T-cell leukemia viruses (HTLV) are closely associated with some human T-cell leukemias and lymphomas. A unique 3' region of the HTLV genome is believed to be involved in HTLV-induced cellular transformation, although the function of this region has yet to be determined. A subgenomic messenger RNA transcribed from this region of HTLV has now been characterized. These results provide direct evidence for the expression of a novel gene in HTLV. 相似文献
18.
19.
Histone phosphorylation: stimulation by adenosine 3',5'-monophosphate 总被引：27，自引：0，他引：27
T A Langan 《Science (New York, N.Y.)》1968,162(853):579-580
Adenosine cyclic 3',5'-monophosphate at a concentration of 10-(7)M causes a four-to sixfold increase in the rate of histone phosphorylation catalyzed by a liver enzyme preparation. This observation suggests a mechanism for the induction of RNA synthesis by those hormones that cause increases in the concentration of cyclic AMP. 相似文献
20.
凝胶电泳技术通常被用于总RNA完整性检测,一般认为28S和18S rRNA条带亮度的比值大于等于2表示总RNA完整性良好,该比值越小表明总RNA降解越严重。为了检测这一标准在水产虾蟹类中是否继续适用,分别对凡纳滨对虾rRNA和mRNA的完整性进行了分析。用TRIzol分离纯化的凡纳滨对虾总RNA经凝胶电泳检测,发现其28S:18S rRNA的比值远小于2;但是以同样的总RNA为模板进行RT-PCR,能顺利扩增出长约1 100 bp的ACT和eEF1A基因序列。进一步的3':5'分析显示这2个内参基因mRNA的3':5' ratio分别为2.79和1.53,直接表明被测mRNA完整性良好。因此,凝胶电泳低估了水产虾蟹类总RNA的完整性,建议采用3':5'分析技术对水产虾蟹类总RNA完整性进行检测。 相似文献