Crystal structure of the RNA-binding domain of the U1 small nuclear ribonucleoprotein A

The crystal structure of the RNA binding domain of the U1 small nuclear ribonucleoprotein A, which forms part of the ribonucleoprotein complex involved in the excision of introns, has been solved. It contains a four-stranded beta sheet and two alpha helices. The highly conserved segments designated RNP1 and RNP2 lie side by side on the middle two beta strands. U1 RNA binding studies of mutant proteins suggest that the RNA binds to the four-stranded beta sheet and to the flexible loops on one end.     

Intracellular transport of microinjected 5S and small nuclear RNAs

The mechanism by which some RNAs are segregated in the cell nucleus was analysed by microinjecting 32 P-labelled total RNA from HeLa cells into the cytoplasm of Xenopus oocytes. Small nuclear RNAs (u1, U2, U4, U5 and U6) migrated into the cell nucleus, where they became 30-60 fold more concentrated than in the cytoplasm. Other RNAs, such as tRNA and 7S RNA, remained in the cytoplasm, while 5S RNA became concentrated in the nucleolus. Studies with lupus erythematosus antibodies showed that the migrating RNAs become associated with oocyte RNA-binding proteins.     

Arrangement of RNA and proteins in the spliceosomal U1 small nuclear ribonucleoprotein particle

In eukaryotic cells, freshly synthesized messenger RNA (pre-mRNA) contains stretches of non-coding RNA that must be excised before the RNA can be translated into protein. Their removal is catalysed by the spliceosome, a large complex formed when a number of small nuclear ribonucleoprotein particles (snRNPs) bind sequentially to the pre-mRNA. The first snRNP to bind is called U1; other snRNPs (U2, U4/U6 and U5) follow. Here we describe the three-dimensional structure of human U1 snRNP, determined by single-particle electron cryomicroscopy at 10 A resolution. The reconstruction reveals a doughnut-shaped central element that accommodates the seven Sm proteins common to all snRNPs, supporting a proposed model of circular Sm protein arrangement. By taking earlier biochemical results into account, we were able to assign the remaining density of the map to the other known components of U1 snRNP, deriving a structural model that describes the three-dimensional arrangement of proteins and RNA in U1 snRNP.     

Conservation between yeast and man of a protein associated with U5 small nuclear ribonucleoprotein

The process of nuclear pre-messenger RNA splicing is similar in Saccharomyces cerevisiae and metazoan cells in that the two-step mechanism is identical and the reaction occurs in a large ribonucleoprotein complex, the spliceosome. Little is known, however, about the degree of conservation of splicing factors other than of the small nuclear RNAs (snRNAs). Yeast counterparts of the metazoan spliceosomal snRNAs (U1, U2, U4, U5 and U6) have been identified but, with the exception of U6, the yeast snRNAs are larger and sequence similarity is limited to short regions. By using antibodies against the yeast PRP8 protein, a pre-mRNA splicing factor of relative molecular mass 280,000 (Mr280K) stably associated with U5 small nuclear ribonucleoproteins (snRNPs), we have now identified an immunologically related protein in HeLa cell nuclear extracts. The HeLa cell protein has an Mr greater than 200K and is associated with purified 20S U5 snRNPs. This is the first report of phylogenetic conservation between yeast and man of a protein splicing factor.     

B2SINE RNA和HEXIM1蛋白相互作用的研究

构建了带FLAG多肽标签的hHEXIM1( HMBA-inducible protein 1)蛋白真核表达载体,在人胚胎肾细胞(human embryonic kidney 293 cells,HEK293 cells)中检测蛋白表达正确后,将该质粒转入小鼠的成纤维细胞(NIH3T3细胞)中,进行anti-FLAG的免...     

数学与逻辑的关系及其发展过程中的相互作用

关于数学与逻辑的关系存在着逻辑主义和直觉主义2种观点,逻辑主义学派认为数学可以化归于逻辑,直觉主义学派认为逻辑可化归于数学。利用现代认识论的思想,论述了数学与逻辑之间的同一性、互补性和差异性,并对它们在发展过程中的相互作用进行了比较全面而深刻的揭示。     

交互界面设计在小家电产品设计中的应用研究

交互设计是互动的设计原则。相对于传统设计,在小家电产品中使用交互设计,通俗易懂,能让用户一目了然、愉悦身心,更方便有效地使用产品。小家电产品的交互界面设计中,应该遵循完整易懂、简单易学、有效有序、方便快捷等原则。     

HIV-1感染与树突状细胞相互作用的研究进展(综述)

树突状细胞(dendritic cells,DC)是目前所知的机体内功能最强的抗原呈递细胞,在免疫应答中发挥重要作用。在AIDS发病机制中有关人类免疫缺陷病毒(HIV)与宿主细胞之间的作用已经有很多报道,但对树突状细胞与HIV感染之间的作用了解较少。近年来的研究发现HIV-1能诱导树突状细胞分化,改编细胞基因表达,上调细胞因子和趋化因子的产生活化T细胞,而不同的DC亚群表达不同的甘露糖C-型凝集素受体(MCLRs)结合HIVgp120,从而促进病毒感染复制和扩散。     

用元的阶刻划U3(2n)

证明了除Ｕ３（２）外,所有射影特殊酉群Ｕ３（２＾ｎ）均可由它们的元的阶加以刻划。     

用元的阶刻划U3(2n)

证明了除U3( 2 )外 ,所有射影特殊酉群U3( 2 n)均可由它们的元的阶加以刻划 .     

腺嘌呤与水分子相互作用的理论研究

应用在密度泛函理论和电负性均衡原理基础上发展起来的原子-键电负性均衡方法（ABEEM），并融合进分子力场中，对比从头计算方法，研究了腺嘌呤（adenine）-水体系中氢键的相互作用，计算了腺嘌呤1水复合物的各种性质，如：优化的几何构型、结合能、稳定性等．揭示了腺嘌呤1水复合物稳定存在的构型是环状的双氢键形式，即水分子与腺嘌呤相互作用时，同时作为受体和供体与腺嘌呤的氢原子和氮原子形成氢键．同时，通过对腺嘌呤1水复合物能量的计算，找到了腺嘌呤与水结合的最优几何位置．计算结果表明，我们的方法和从头计算及实验结果相比有很好的一致性，验证了我们模型的合理性和参数的可靠性．     

拟南芥AtHHR2与DREB2C的相互作用研究

已有研究表明拟南芥Highly Homologous RING domain 2(At5g43200,命名为AtHHR2)基因在盐胁迫中起正调控作用,并且其同源基因AtHHR3基因在酵母双杂交实验筛选中与DREB2C基因有相互作用.本研究利用体外、体内蛋白质相互作用实验以及生物化学方法进一步探究了AtHHR2的功能性.体外Pull-down实验证实了AtHHR2与DREB2C有体外的相互作用.体外泛素化实验进一步验证了它们之间的相互作用,且AtHHR2起到E3连接酶的作用.为了进一步确定它们的关系,我们用双分子荧光互补实验,在体内分别验证了AtHHR2与DREB2C之间确实有相互作用.综上所述在拟南芥中AtHHR2与DREB2C有相互作用关系,且AtHHR2起到E3连接酶的作用.     

胚胎干细胞中DPPA2和DPPA4蛋白相互作用的研究

本文分别构建了小鼠胚胎干细胞的带FLAG多肽标签的DPPA和带HA多肽标签的DPPA4蛋白真核表达载体.将该质粒转入小鼠成纤维细胞HEK293中进行细胞体内表达,并利用免疫印记和免疫共沉淀技术证明了DPPA2和DPPA4蛋白在细胞内可以相互作用.因此,提出了在胚胎干细胞的自我更新和分化等过程中,DPPA2和DPPA4蛋白相互作用的结论.     

染料分子与牛血清蛋白相互作用的研究

应用定量结构-性质关系技术,通过对染料分子与牛血清蛋白的增强共振散射光谱的分析,研究了它们之间的相互作用.经过遗传算法对染料分子结构描述符的筛选,针对最大散射波长及其强度,分别采用了3个及6个染料分子结构描述符建立了两个定量结构-性质关系模型,进而推测染料分子与牛血清蛋白主要为分子间非化学键作用,染料分子被吸附于牛血清蛋白的表面.     

长非编码RNA与SAFB1相互作用中RNA二级结构的作用

为探究RNA与SAFB1蛋白相互作用过程中RNA二级结构的作用.采用足迹法确定SAFB1与LINC-PINT-1特定的结合区域,在此基础上根据RNA结构分析研究SAFB1结合区域所具有特定的二级结构.最后通过凝胶迁移率实验论证该二级结构在RNA与SAFB1蛋白结合中的作用.结果显示:在针对LINC-PINT-1的亚克隆发现只有包含30～55 nt区域的亚克隆才能维持RNA结合区域的二级结构,并且证实了LINC-PINT-1与SAFB1蛋白相互作用依赖于特定的RNA二级结构.结果表明:长非编码RNA与SAFB1蛋白相互作用或依赖于特定的RNA二级结构,本研究为RNA与蛋白质相互作用的分子机制研究提供了有力的理论实验支撑.     

1-(2-吡啶偶氮)-2-萘酚-磺酸与蛋白质结合反应的光谱法研究

采用荧光光谱法和吸收光谱法研究了1-(2-吡啶偶氮)-2-萘酚-磺酸(PAN-S)与牛血清白蛋白(BSA)的结合反应.研究表明,PAN-S对BSA的荧光猝灭机理为静态猝灭.测定了反应的结合常数(K=5.32×105～8.53×105L·mol-1)、荧光猝灭常数(Ksv=7.08×105L·mol-1)及结合位点数(n=2.88).进一步通过同步荧光法研究了PAN-S对BSA构象的影响,认为PAN-S主要结合在BSA的色氨酸残基附近.研究发现,PAN-S与BSA之间存在着类似于其同阳离子表面活性剂的静电作用.     

基于信息披露质量的大股东股权质押与审计定价关系研究

近年来，股权质押因其便利和快捷逐渐成为广受欢迎的融资方式。大股东为避免控制权转移和自身杠杆化风险，会对上市公司资源产生掏空效应和盈余管理动机，进而加大公司的经营风险和会计师事务所的审计风险，并影响审计定价。本文以2014~2018年间深市A股制造业上市公司为研究对象，从信息披露质量的视角验证了大股东股权质押与审计定价之间的关系。研究发现：大股东股权质押与审计定价呈正相关关系；上市公司信息披露质量与审计定价呈负相关关系；信息披露质量对大股东股权质押与审计定价存在负向调节作用。