共查询到20条相似文献,搜索用时 19 毫秒
1.
Stat5及JAK-Stat5通路 总被引:1,自引:0,他引:1
信号转导与转录因子(Stats)家族是一个由7个成员组成的转录调控家族,其中Stat5由于在多种细胞因子刺激时均可起到重要作用而引起了广泛的关注。Stat5具有两种不同类型,即Stat5a和Stat5b,它们均可被多种细胞因子所激活,启动JAK-Stat5信号通路,从而调节相应基因的表达。在两种Stat5的激活中,特殊位点的丝氨酸和酪氨酸的磷酸化对Stat5的激活起重要的作用。对信号通路严格的控制对于生物体来说具有重要的意义,在JAK-Stat5信号通路中,以SOCS3为代表的SOCS家族对JAK-Stat5的负反馈调节具有重要作用。 相似文献
2.
Subha R. Das 《Nucleosides, nucleotides & nucleic acids》2013,32(10):668-677
To extend the potential of 5′-noraristeromycin (and its enantiomer) as potential antiviral candidates, the enantiomers of the carbocyclic 5′-nor derivatives of 5′-methylthio-5′-deoxyadenosine and 5′-phenylthio-5′-deoxyadenosine have been synthesized and evaluated. None of the compounds showed meaningful antiviral activity. 相似文献
3.
曹文辉 《国外医学:分子生物学分册》1995,17(2):86-88
5-HT5受体又分为5-HT5A及5-HT5B两种亚型受体,5-HT5A受体主要存在于小脑,大脑皮层,海马等脑区,5-HT5B受体仅在海马CA1区,缰核,背侧缝际核发现,该受体与麦角胺(Ergo-tamine),5-羧基酰氨基色胺(5-Carboxamidotryptamine,5-CT),5-HT,美西麦角(Methysergide)等配体亲和力较大,可能与5-HT 1D受体有某种功能联系,5-HT6受体主要在纹状体,边缘脑和大脑皮层等脑区表达,这类受体与三环类抗精神病药及抗抑郁药有高亲和力反应,提示它参与某些精神疾病的发生与治疗。 相似文献
5.
Richard Y.-H. Wang Lan-Hsiang Huang Melanie Ehrlich 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,696(1):31-36
Bacteriophage XP-12-infected Xanthomonas oryzae have been found to be a source of a kinase preparation which converts m5dCMP to m5dCDP and then to m5dCTP using ATP as the phosphate donor. Optimal formation of the triphosphate required the presence of creatine phosphate and creatine kinase. In the presence of dGTP, dTTP and dATP, Escherichia coli DNA polymerase I and T4 DNA polymerase catalyzed the incorporation of m5dCTP into DNA just as efficiently as that of dCTP. Neither dTMP nor dCMP served as substrate for the m5dCMP monophosphate kinase. Analogous preparations from uninfected X. oryzae were unable to phosphorylate m5dCMP. 相似文献
6.
7.
《Phytochemistry》1996,42(5):1259-1262
Methyl 5′,5′,5′-trifluorojasmonate was synthesized as an antimetabolic analogue of methyl jasmonate. It induced potato tuber formation more effectively than methyl jasmonate and inhibited the growth of rice seedlings and the germination of lettuce and radish seeds. These results suggest that epijasmonic acid itself has potato tuber-inducing activity and that the hydroxyl group of tuberonic acid is not necessary for this activity. 相似文献
8.
Moheshwar Sharma Yi X. Li Miroslav Ledvina Miroslav Bobek 《Nucleosides, nucleotides & nucleic acids》2013,32(9-10):1831-1852
Abstract A series of 5′-substituted analogs of toyocamycin were prepared by condensation of silylated 4-amino-6-bromo-5-cyanopyrrolo[2,3-d]pyrimidine with protected 5-azido-5-deoxy- or 5-fluoro-5-deoxyribofuranose followed by debromination and deblocking. Alternatively, 5′-azido-5′-deoxytoyocamycin was prepared by azidation of toyocamycin. Conversion of the 5-nitrile function of the toyocamycin derivatives into a carboxamide or a thiocarboxamide gave the corresponding analogs of sangivamycin or thiosangivamycin while reduction of the 5′-azido-5′-deoxy nucleosides provided 5′-amino-5′-deoxy derivatives. 相似文献
9.
《Nucleosides, nucleotides & nucleic acids》2013,32(4-7):685-688
5′-Deoxy-5′-S-allenylthioadenosine 1 and 5′-deoxy-5′-S-propnylthioadenosine 2, derived from adenosine, were prepared. 1 and 2 caused irreversible inactivation of AdoHcy hydrolase. ESI mass spectra analysis of the inactivated enzyme demonstrated that 1 and 2 were type II “mechanism-based” inhibitors. 相似文献
10.
11.
Summary The distribution of 5-nucleotidase activity in rat liver shows a sexual dependence. In male liver the activity in the bile canalicular wall is most pronounced, whereas the activity at the sinusoidal border of the liver parenchymal cell is slightly more in the female rat. Castration and treatment with sex hormones change the distribution pattern. The greatest variations in enzyme activity are seen at the bile canalicular site of the liver cell. These changes are probably an expression of the altered functional state of the liver cell. 相似文献
12.
M. J. Hardonk 《Histochemistry and cell biology》1968,12(1):1-17
Summary The distribution of 5-nucleotidase in several tissues of rat and mouse has been investigated. The enzyme is greatly specific in dephosphorylating 5-nucleotides. Two 5-nucleotidases seem to exist: one showing greatest activity at pH 5.0, while the other is most active at pH 7.0–7.5. The localization of these two enzymes is not identical. At the acid pH the deoxyribonucleotides are dephosphorylated faster than the ribonucleotides, while at the neutral pH the ribonucleotides are hydrolysed more rapidly. In contrast to the non-specific phosphatases the nucleotidases can be stimulated by magnesium and manganese ions. The acid nucleotidase can be considered as a lysosomal enzyme. The neutral nucleotidase can be involved in transport processes in capillaries and sinusoids. Other localizations of the enzyme suggest a role of the enzyme in the catabolism of nucleic acids. 相似文献
13.
Summary To get more insight in the function of 5-nucleotidase catabolic and anabholic processes were investigated in which 5-nucleotides are involved. The catabolism of adenosine-5-monophosphate was studied by investigating the reaction products obtained after incubation of homogenates of several organs of rat and mouse with adenosine-5-monophosphate and with adenosine. Two experimental tumours of the mouse were investigated in the same way. It was found that in tissues containing a high activity of 5-nucleotidase other enzymes involved in the catabolism of 5-nucleotides, such as nucleosidase, adenosine deaminase and adenosine-5-monophosphate deaminase could also be demonstrated.The anabolic processes in which 5-nucleotides are involved had been studied by investigating the incorporation of tritium-labeled thymidine in several tissues of the mouse. It appeared that in cells showing a high 5-nucleotidase activity no incorporation of radioactive thymidine could be found, while in cells showing incorporation of thymidine enzyme activity could not be demonstrated.A discussion is given about the possible role of 5-nucleotidase in the control of nucleic acid biosynthesis and in the catabolism of nucleic acids.Abbreviations used DNA
deoxyribonucleic acid
- RNA
ribonucleic acid
- AMP
Adenosine-5-monophosphate
- ADP
Adenosine-5-diphosphate
- ATP
Adenosine-5-triphosphate
- IMP
Inosine-5-monophosphate
- GMP
Guanosine-5-monophosphate
- GDP
Guanosine-5-diphosphate
- GTP
guanosine-5-triphosphate
- CMP
Cytidine-5-monophosphate
- CDP
Cytidine-5-diphosphate
- CTP
Cytidine-5-triphosphate
- UMP
Uridine-5-monophosphate
- UDP
Uridine-5-diphosphate
- UTP
Uridine-5-triphosphate
- TMP
Thymidine-5-monophosphate
- TDP
Thymidine-5-diphosphate
- TTP
Thymidine-5-triphosphate
- Ado
Adenosine
- Ad
Adenine
- Ino
Inosine
- Hypox
Hypoxanthine
- Xanth
Xanthine
- Xantho
Xanthosine
- Guano
Guanosine
- Gua
Guanine
- Ura
Uracil
- U
Uridine
- Cyt
Cytidine
- Cyto
Cytosine
- Thym
Thymidine
The corresponding deoxy-compounds have been indicated with the prefix d for instance dCMP, deoxycytidine-5-monophosphate. 相似文献
14.
Summary Determinations of pH activity curves and of Michaelis constants of 5-nucleotidases in organs of rat and mouse indicate the heterogenity of the enzyme in these tissues. Electrophoretic analyses of homogenates and cell component fractions reveal the presence of 5-nucleotidase isoenzymes in the investigated tissues. At the acid as well as at the neutral pH five isoenzymes were found. In addition three alkaline phosphatases were found in the rat; in the mouse four alkaline phosphatase isoenzymes could be demonstrated. The different combinations of 5-nucleotidase isoenzymes in the investigated tissues possibly indicate different functions of the isoenzymes. A discussion is given of the correlations between the electrophoretic results and the histochemical findings. 相似文献
15.
1.某种生物体细胞中染色体数目为 2 n=4 ,请在 1个直角坐标系内用曲线图表示此种生物的细胞在进行减数分裂时各个时期的 DNA分子数目的变化 (注 :横坐标表示细胞周期 ,纵坐标表示 DN A分子数目。)。2 .新华社北京 6月 2 6日电 (记者李斌、谢培 ) 今天是人类历史上值得纪念的一天 ,来自科技部和中国科学院的消息说 ,人类基因组的工作草图已经绘制完毕并于今天向全世界公布。众所周知 ,科学和技术对人类的应用有其正负效应 ,尽管人类基因组计划得到了广泛的支持 ,但还是有一些人对这一计划表示了自己的忧虑。针对这一计划将对人类产生的影… 相似文献
16.
丙型肝炎病毒(HCV)RNA5′-非编码区(5′-NTR)由341个核苷酸组成,形成4个茎-环二级结构,5′-NTR二级结构及某些部分单链序列的核苷酸组成是病毒翻译起始的先决条件.5′-NTR中的大部分核苷酸序列组成内部核糖体进入位点(IRES),在宿主细胞蛋白质因子La自身抗原、eIF3、多聚嘧啶区结构蛋白(PTB)、多聚胞嘧啶结合蛋白(PCBP-1、2)等的作用下,形成复杂的翻译起始复合物,对HCV的翻译过程进行精确调控,完成帽状结构形成非依赖性的蛋白翻译过程.HCV
RNA 5′-NTR翻译过程的分子生物学机制的研究,将有助于HCV治疗新方法和新途径的探索. 相似文献
17.
Summary This study was undertaken to investigate the mechanism of chemical radiosensitization by halogenated bases incorporated into DNA. Radiation-induced base and sugar-phosphate backbone damage to 5-bromouridine-5-monophosphate (5-BrUMP) was monitored using a flow system connected in series with a recording spectrophotometer, a bromide (Br–)-specific ion analyzer and a Technicon auto-sampler. The system was used to assay loss of UV-absorbing 5,6 double-bond, release of Br– and inorganic phosphate (Pi) release using an automated colorimetric method, as a function of gamma-ray dose. Results obtained with radical scavengers indicate that, unlike non-halogenated nucleotides where the hydroxyl radical (· OH) is the principal damaging species, 5-BrUMP is damaged by the hydrated electron (e
aq
–
), hydrogen atom (H·) and · OH, producing a high yield of base damage and Br– and Pi release in anoxia. Another novel feature of 5-BrUMP radiolysis is that oxygen, by convertinge
aq
–
and H· to the unreactive superoxide radical anion (0
2
–
), has a protective effect on both base and phosphate ester damage. Under · OH-scavenging conditions, where the radiation yield of reductive debromination is 3.8, there is some Pi release, suggesting the possibility of intramolecular hydrogen atom transfer from the sugar ring to the 5-uracilyl radical and subsequent sugar-phosphate bond cleavage. This hypothesis is supported by the action of oxygen and thiols in modifying thee
aq
–
-mediated sugar-phosphate damage. 相似文献
18.
一、非选择题1.有一实验现象:将生理状况相同的胚芽鞘分成甲、乙两组,甲组给单侧光照,乙组不给光照。同样培养一段时间后,甲组向光弯曲生长,乙则直立向上生长。请简答下列问题: (1)本实验结果能证明胚芽鞘具有的生理特性。(2)实验中胚芽鞘的生长方式与植物生长素的调节作用有关。甲组受到单侧光照后,胚芽鞘上部生长素分布的特点是,由于生长素的生理作用而使其向光弯曲生长;此时乙组未受到光照,生长素在胚芽鞘中可能分布,因而导致其直立向上生长。(3)作为对照,若要使乙组同时也受到光照,你会如何设计乙组实验装置?请将你的设计图示于下,并… 相似文献
19.
1.PTC是一种无毒但有苦味的物质 ,有的人极易尝出它的苦味 ,有的人则极难尝出它的苦味。现有 859人参加试验 ,尝试不同浓度的 PTC的苦味。尝试的办法是先从最稀的溶液开始 ,到尝出有苦味的溶液为止。例如 ,某人尝到第 10号溶液才感觉到苦味 ,他 (她 )就是第 10号溶液柱形图中的 1个人。结果如下列柱形图所示。 1号溶液的浓度是 10 0 0 ml溶液中有 2 .6 g PTC晶体 (0 .2 6 % ) ,以后各号溶液依次稀释 1倍。 试根据下图回答 :(1) PTC浓度最高的溶液是号 ,这些人对PTC苦味。(2 )尝到 PTC苦味人数最多的溶液是号 ,其溶液浓度为。(3)… 相似文献