Arrangement of human immunoglobulin heavy chain constant region genes implies evolutionary duplication of a segment containing gamma, epsilon and alpha genes

Cosmid clones containing the human gamma, epsilon and alpha heavy chain constant region genes and an epsilon pseudogene have been isolated. All these genes have a switch sequence detectable by hybridization. We have studied overlapping cosmids covering two separate regions of the genome, and the gene order in each of these regions was found to be gamma-gamma-epsilon-alpha. This implies an evolutionary duplication in this multigene family involving gamma, epsilon and alpha genes.     

树鼩IL-2Rα(CD25)基因的分离、鉴定及表达分析

CD25是CD4+CD25+调节性T细胞的重要标记分子.树鼩是一种重要的人类疾病动物模型,但是,树鼩的CD25基因还是未知.我们以树鼩脾脏RNA为模板,对树鼩白介素-2受体基因alpha链(tsCD25)进行了RT-PCR(逆转录-聚合酶链式反应),获得了一个816bp的开放阅读框.TsCD25 cDNA编码一个由271个氨基酸组成的分子量为30.9 ku的蛋白多肽.预测的tsCD25包含2个Sushi结构域、2个N-糖基化位点和多个O-糖基化位点.tsCD25和灵长类CD25在氨基酸水平上的同源性为65.3%～66.4%.RT-PCR检测发现,tsCD25 mRNA分布于树鼩的外周血、脾脏和肺,并受PMA 和 ionomycin 刺激的调节.我们的结果为下一步制备tsCD25单克隆抗体,抑制CD4+CD25+Tregs功能以及开展有关的研究工作奠定了基础.     

GTPase inhibiting mutations activate the alpha chain of Gs and stimulate adenylyl cyclase in human pituitary tumours

A subset of growth hormone-secreting human pituitary tumours carries somatic mutations that inhibit GTPase activity of a G protein alpha chain, alpha(s). The resulting activation of adenylyl cyclase bypasses the cells' normal requirement for trophic hormone. Amino acids substituted in the putative gsp oncogene identify a domain of G protein alpha-chains required for intrinsic ability to hydrolyse GTP. This domain may serve as a built-in counter-part of the separate GTPase-activating proteins required for GTP hydrolysis by small GTP-binding proteins such as p21ras.     

绵羊脂联素受体2基因生物信息学分析

采用生物信息学方法对绵羊(兰州大尾羊)AdipoR2基因及其所对应蛋白质进行了分析.结果显示,AdipoR2基因全长1 809 bp,编码386个氨基酸多肽蛋白.核苷酸和氨基酸的同源性与山羊最高,分别为99.1%和99%,非洲爪蟾最低,分别为68.2%和78.5%.兰州大尾羊AdipoR2编码蛋白二级结构中α-螺旋占23.06%,β-片状占27.72%,无规则卷曲占49.22%.ADIPOR2蛋白为跨膜蛋白,N-端位于胞内,C-端位于胞外,由7个跨膜结构域组成.分析表明,绵羊AdipoR2基因由7个外显子和6个内含子组成,核苷酸序列变异以转换为主,转换/颠换比值为2.072.不同物种间绵羊与山羊AdipoR2核苷酸序列间变异最小(0.9%).系统发育分析表明,绵羊与山羊也首先聚为一类,推测绵羊与山羊的分歧时间大约在0.225百万年前.这些结果为进一步分析绵羊脂联素受体2(AdipoR2)基因功能及其所介导的脂联素功能奠定了理论基础.     

人胰岛素A链与B链基因的化学合成,克隆与表达

采用大肠杆菌密码子，用化学法分别合成人胰岛素２１个氨基酸的Ａ链，３０个氨基酸的Ｂ链，并在基因的５端引入甲硫氨酸密码子，尾部加入终止密码，两端加入限制性内切酶，Ａ链为８３个核苷酸，Ｂ链为１１０个核苷酸，经纯化后的寡聚核苷酸进行酶促连接反应后，分别克隆了人胰岛素Ａ、Ｂ链基因，然后选用ＰＬ启动子，构建了以牛生长前１３４个氨基酸的大片段基因，分别与人胰岛素Ａ链、Ｂ链基因的融合基因的融合基因的表达质粒ＰＬＷ     

青海半细毛羊血清中SOD、GSH-PX、MDA含量的测定

对饲养在青海省湟源县的10只青海半细毛羊的血清T-SOD、Cu-Zn-SOD、Mn-SOD、GSH-PX、MDA含量进行了测定,结果分别是:(261 67±37 27)NU/mL、(124 24±19 95)NU/mL、(137 42±40 07)NU/mL、(58 70±14 76)活力单位、(0 04±0 13)nmol/mL。其中SOD和GSH-PX含量在大部分动物常值之间,但MDA含量极低。     

Reconstitution by MHC-restricted peptides of HLA-A2 heavy chain with beta 2-microglobulin, in vitro

Cytotoxic T lymphocytes kill virally infected cells when they detect antigenic fragments presented by class I major histocompatibility complex (MHC) antigens (HLA in humans). The crystal structures of HLA-A2 and HLA-Aw68 reveal that peptide-antigen forms an integral part of the HLA structure, being retained in a prominent groove even after purification and crystallization. Here we report that the heavy chain and beta 2-microglobulin of HLA-A2, after separation and fractionation in denaturants, reassemble efficiently under renaturing conditions only in the presence of MHC-restricted peptides. A complex of heavy chain, beta 2-microglobulin, and viral peptide in the ratio 1:1:1 is formed in up to 46% yield. Reconstitution is not stimulated by either of two peptides not restricted to HLA-A2. The reconstituted complex of HLA-A2 and the influenza virus (B/Lee/40) nucleoprotein peptide, Np (85-94), crystallizes under conditions previously used to crystallize HLA-A2. Peptide-linked folding and assembly suggests mechanisms for the unusual capacity of HLA to bind many peptides of diverse sequence.