电压依赖性钙通道

电压依赖性钙通道分为L、N、T三种类型,L型通道是由四个结构相似的亚区组成的跨膜蛋白亲水孔道,每个亚区又由六个α螺旋构成,其中一个为带正电的α螺旋,可能构成电压敏感装置。通道内有两个钙亲和位点,对钙的选择通透由亲和位点和离子间静电作用造成。钙通道的调制表现为对通道单位电流值、通道开放数目、电压依赖性,以及时间依赖性单独或复合的影响,通道蛋白磷酸化介导了许多生物活性物质对通道功能的调制。     

BKCa通道的结构与功能

BKCa通道将细胞膜电特性与细胞信号系统联系在一起,在细胞功能实现中起着重要作用。该通道广泛且又较高密度地表达于许多物种的多种组织,其分子结构复杂,丰富的超家族成员具有各自不同的表达分布。BKCa通道的分子结构由α亚单位和β亚单位构成,其中α亚单位形成通道的孔道区和活性调节区域,β亚单位修饰通道活性的调节特性。BKCa通道开放几率大、电导率高、调控位点多,并且不同的超家族成员表现出不同的功能特征,如细胞膜电位感受性、细胞内游离钙离子敏感性等。文章概述BKCa通道的分子结构和功能特征。     

9种Na+通道mRNA在5个不同发育阶段大鼠16种组织中表达及变化趋势

电压-门控Na⁺通道由1个可单独发挥作用的α亚单位和2～4个起辅助作用的β亚单位构成,在可兴奋细胞动作电位的产生及传导等过程中起重要作用.采用RT-PCR法对5个不同发育阶段(P1、P9、P40、P80、P120)Wistar大鼠16种不同组织的9种Na⁺通道α亚单位及1种β亚单位的mRNA进行检测发现：同种类型Na⁺通道mRNA在大鼠不同组织中的表达不同,不同类型Na⁺通道mRNA在大鼠同一组织中的表达不同.其中,神经系统和心肌组织中Na⁺通道mRNA的表达最高,随着日龄的增加,Na⁺通道mRNA在不同组织中表达的变化趋势不同.Na⁺通道在全身组织中的广泛分布及随发育周期的不同变化趋势,为离子通道病的研究及治疗提供了理论基础.     

核盘菌AROM蛋白的三级结构分析

核盘菌编码AROM蛋白的arom基因已经被克隆测序,本文根据该基因翻译的氨基酸序列用同源模建方法和从头模建方法分析了AROM蛋白各结构域的三级结构和功能位点,以及该蛋白二聚体可能的组装方式。结果表明,核盘菌AROM蛋白的脱氢奎尼酸合酶结构域进一步由N-端含有一个Rossmann折叠的α/β结构域和C-端的α螺旋结构域组成;5-烯醇丙酮酰莽草酸-3-磷酸合酶结构域则由两个相似结构域组成,每个结构域含有不同拷贝数的β折叠和α螺旋;莽草酸激酶结构域的N-端由三个β折叠组成;脱氢奎尼酸酶结构域为(α2β2)3多肽,在N-端有一对反平行的β链,在C-端有loop环;莽草酸脱氢酶结构域含有一个由α/β组成的催化结构域和一个含有Rossmann折叠的NADPH结合结构域。     

Cloning, sequence analysis and expression profiling of glutathione Stransferase omega 1 gene from Locusta migratoria (Orthoptera:Acridoidea )

谷胱甘肽S-转移酶(glutathione S-transferase,GST)是一类广泛分布的多功能超家族酶系,其中Omega家族GST在昆虫体内担负重要生理功能.为探讨飞蝗Locusta migratoria Omega家族GST功能,利用RT-PCR技术克隆得到1条飞蝗谷胱甘肽S-转移酶Omega家族基因全长cDNA,命名为LmGSTol(GenBank登录号:JQ750592).该基因开放阅读框长738 bp,编码245个氨基酸.该酶含有N-端和C-端2个结构域,N-端结构域由5个β-折叠和3个α螺旋组成,包括4个GSH结合位点;C-端结构域由8个α螺旋组成,含有5个底物结合位点.Real-time PCR 结果表明,LmGSTo1在飞蝗不同龄期均有表达,在胃盲囊和中肠表达量较低,在前肠、马氏管、肌肉和脂肪体表达量较高;溴氰菊酯处理可导致LmGSTo1表达水平显著下降.这些结果为进一步研究LmGSTo1基因功能提供了依据.     

烟碱样乙酰胆碱受体的离子通道特性

烟碱样乙酰胆碱受体(AChR)是一种配基门控性离子通道,由5个亚单位(α_2βγα)构成。利用非洲蟾蜍卵母细胞的表达系统可以研究AChR的通道特性和各亚单位所起的作用。电鳗电器官AChR和小牛肌AChR之间门控特性的差别,主要是由δ亚单位决定的;而小牛肌成年型AChR与胚胎型AChR之间的差别,则由ε亚单位决定。     

整合素的构象变化与亲和力调控

整合素(integrin)是由α、β两个亚单位通过非共价键连接而组成的异源二聚体。每种α、β亚单位都是含有多种结构域的大分子量Ⅰ型穿膜糖蛋白。它在细胞与细胞间、细胞与基质间相互作用的过程中发挥着十分关键的作用。整合素多种结构域的空间排列决定了其构象特征,而整合素的不同构象状态与其亲和力呈高度相关。对αVβ133整合素晶体结构的解析使我们对整合素的结构与功能有了更进一步的理解。     

家蝇Prohibitin基因的生物信息学分析

为对家蝇Prohibitin蛋白序列进行生物信息学分析,从而为该基因功能研究奠定基础。利用在线分析程序和相关工具软件分析Prohibitin蛋白的理化性质、结构域、并预测其空间结构和功能。结果表明家蝇Prohibitin蛋白由277个氨基酸组成,分子量为30.54 k Da,理论等电点为5.26,为稳定蛋白,有跨膜区,但不含信号肽,该蛋白属于PHB保守结构域家族,亚细胞定位于细胞质,二级结构以α-螺旋为主。蛋白同源性比对结果显示,昆虫中的Prohibitin蛋白具有较高的同源性。这些分析结果可为今后深入研究该蛋白的结构特征和功能提供参考。     

G蛋白βγ亚单位介导的信号转导途径

跨膜信息传递有关的Ｇ蛋白由α、β和γ亚单位所组成,受体激动后,引起ＧＴＰ与α亚单位结合,导致Ｇα与Ｇβγ分离。近年来发现Ｇα、受体本射和许多效应分子如Ｋ＾＋通道、Ｇａ＾２＋通道、磷脂酶Ｃ－β、腺苷酸环化酶、酷氨酸、ＭＡＰＫ和受体激酶等都受Ｇβγ的调节,Ｇβγ同Ｇα一样均可引起效应蛋白的激活,在细胞信号转导中起同样重要作用,共同介导一系列的生物学效应。     

太子参谷胱甘肽-S-转移酶基因家族生物信息学及表达分析

GSTs (glutathione-S-transferases)是一个普遍存在于植物体内,多基因家族编码的多功能蛋白酶。为研究GSTs基因家族在太子参中对其生长发育以及活性成分合成调控的潜在功能,该文基于隐马尔可夫模型在太子参中鉴定到30个谷胱甘肽-S-转移酶(PhGSTs)的基因家族成员。结果表明:30个PhGSTs基因同时具有高度保守的N-端结构域和复杂多变的C-端结构域,分属于6个亚家族,有10个motif区,其中motif1、motif 2、motif 3同属于所有家族,motif 4仅属于Tua亚家族。PhGST蛋白质三级结构有明显的相似之处,N端主要由3个α螺旋和4个β折叠构成βαβαββα结构域,C端均由α螺旋构成,不同亚家族的C端α螺旋数目及组合方式各不相同,但始终维持相似的三维结构。PhGST基因在太子参植物中具有不同的组织表达特异性,PhGSTU1、PhGSTU8、PhGSTU9等在太子参块根中优势表达,PhGSTF2在茎和叶中优势表达。水分胁迫处理后有4个基因积极响应干旱胁迫,PhGSTZ1的响应最为明显;同时也有PhGSTU8、PhEFB1γ3等4个基因随土壤含水量增加呈上调表达。该文鉴定出30个PhGST基因,并分析了其在太子参中的表达模式,为PhGSTs基因家族在太子参活性成分的合成调控及逆境响应等生理过程中的功能研究奠定理论基础。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.