A novel putative tyrosine kinase receptor encoded by the eph gene

Growth factors and their receptors are involved in the regulation of cell proliferation and also play a key role in oncogenesis. In this study, a novel putative kinase receptor gene, termed eph, has been identified and characterized by molecular cloning. Its primary structure is similar to that of tyrosine kinase receptors thus far cloned and includes a cysteine-rich region in the extracellular domain. However, other features of the sequence distinguish the eph gene product from known receptors with tyrosine kinase activity. Thus the eph protein may define a new class of these molecules. The eph gene is overexpressed in several human carcinomas, suggesting that this gene may be involved in the neoplastic process of some tumors.     

Probing gene expression in live cells, one protein molecule at a time

We directly observed real-time production of single protein molecules in individual Escherichia coli cells. A fusion protein of a fast-maturing yellow fluorescent protein (YFP) and a membrane-targeting peptide was expressed under a repressed condition. The membrane-localized YFP can be detected with single-molecule sensitivity. We found that the protein molecules are produced in bursts, with each burst originating from a stochastically transcribed single messenger RNA molecule, and that protein copy numbers in the bursts follow a geometric distribution. The quantitative study of low-level gene expression demonstrates the potential of single-molecule experiments in elucidating the workings of fundamental biological processes in living cells.     

鸡PDK4基因的组织表达分析

利用Real Time-PCR 的方法研究PDK4 基因在肉鸡中的组织表达规律尧在不同生长阶段的组织表达趋势及在不同生长速度肉鸡中的组织差异表达遥结果表明院渊1冤鸡PDK4 基因在肌肉组织渊包括腿肌尧胸肌尧心脏冤表达最高曰渊2冤肌肉组织PDK4 基因在12 胚龄的表达较低袁初生1 日龄时表达最高袁此后有所下降曰渊3冤在垂体尧胸肌尧心脏中袁PDK4 基因在杏花鸡中的表达高于白洛克鸡袁而在腿肌中的表达趋势相反曰胸肌中袁PDK4 基因表达在体重轻组中表达高于重组袁而在腿肌中的表达趋势相反遥     

The product of the human c-erbB-2 gene: a 185-kilodalton glycoprotein with tyrosine kinase activity

Antibodies were raised against a synthetic peptide corresponding to 14 amino acid residues at the COOH-terminus of a protein deduced from the human c-erbB-2 nucleotide sequence. These antibodies immunoprecipitated a 185-kilodalton glycoprotein from MKN-7 adenocarcinoma cells. Incubation of the immunoprecipitates with (gamma-32P)ATP resulted in the phosphorylation of this protein on tyrosine residues. These results indicate that the human c-erbB-2 gene product is the 185-kilodalton glycoprotein that is associated with tyrosine kinase activity. Although the c-erbB-2 protein was predicted to encode a protein very similar to epidermal growth factor (EGF) receptor, EGF did not stimulate this kinase activity either in vivo or in vitro.     

Protein tyrosine kinase Wee1B is essential for metaphase II exit in mouse oocytes

Waves of cyclin synthesis and degradation regulate the activity of Cdc2 protein kinase during the cell cycle. Cdc2 inactivation by Wee1B-mediated phosphorylation is necessary for arrest of the oocyte at G2-prophase, but it is unclear whether this regulation functions later during the metaphase-to-anaphase transition. We show that reactivation of a Wee1B pathway triggers the decrease in Cdc2 activity during egg activation. When Wee1B is down-regulated, oocytes fail to form a pronucleus in response to Ca(2+) signals. Calcium-calmodulin-dependent kinase II (CaMKII) activates Wee1B, and CaMKII-driven exit from metaphase II is inhibited by Wee1B down-regulation, demonstrating that exit from metaphase requires not only a proteolytic degradation of cyclin B but also the inhibitory phosphorylation of Cdc2 by Wee1B.     

茶树甲羟戊酸激酶基因CsMVK克隆及表达特性分析

[目的]克隆茶树甲羟戊酸激酶基因(CsMVK),分析其生物学信息及在不同组织及乌龙茶做青过程中的表达特性,为研究茶叶加工过程中香气形成机制提供参考.[方法]RT-PCR扩增CsMVK基因,应用生物信息学软件对其编码蛋白(CsMVK)的氨基酸序列进行预测分析,通过实时荧光定量PCR(qPCR)分析CsMVK在茶树不同组织及乌龙茶做青过程中的表达特性.[结果]克隆获得的CsMVK基因(GenBank登录号MF668187)全长1455 bp,开放阅读框(ORF)长度为1164 bp,编码387个氨基酸,蛋白质分子量41.18 kD,理论等电点(pI)5.88.CsMVK蛋白具有GHMP_kinases_N domain和GHMP_kinases_C domain 2个功能结构域,定位于细胞质中,不存在跨膜结构和信号肽.系统发育进化树分析结果显示,CsMVK与三七、常春藤的MVK聚为一类,表明茶树与三七、常春藤的亲缘关系最近.qPCR检测结果显示,CsMVK基因在果实中的表达量显著高于其他组织(P<0.05,下同),在不同组织中的表达量排序为:果实>根>叶>茎>花;在乌龙茶做青过程中,从鲜叶到晒青叶,CsMVK基因的表达量上升,晒青到一摇过程中表达量下降,经过3次摇青,其表达量持续升高并在杀青前达最大值,与其他做青阶段差异显著.[结论]CsMVK基因表达与茶叶香气品质形成有关.     

Specific expression of hepatitis B surface antigen (HBsAg) in transgenic mice

Two transgenic mice were obtained that contain in their chromosomes the complete hepatitis B virus (HBV) genome except for the core gene. These mice secrete particles of HBV surface antigen (HBsAg) in the serum. In one mouse, HBV DNA sequences that had integrated at two different sites were shown to segregate independently in the first filial generation (F1) and only one of the sequences allowed expression of the surface antigen. Among these animals the males produced five to ten times more HBsAg than the females. A 2.1-kilobase messenger RNA species comigrating with the major surface gene messenger RNA is expressed specifically in the liver in the two original mice. The results suggest that the HBV sequences introduced into the mice are able to confer a tissue-specific expression to the S gene. In addition, the HBV transgenic mice represent a new model for the chronic carrier state of hepatitis B virus infection.     

羊口疮病毒B2L基因的原核表达、纯化及反应原性分析

【目的】克隆和表达羊口疮病毒(ORFV)的B2L基因,进而纯化并分析其反应原性.【方法】根据GenBank已发表的ORFV(GQ328006)的B2L基因序列设计一对特异引物,以提取阳性临床样品的总DNA为模板,通过PCR方法获得ORFV的B2L基因,将该基因片段连接至原核表达载体pET-30a(+)上,获得重组质粒pET-30a(+)-B2L.将此重组质粒转化BL21(DE3)感受态细胞,挑取单克隆进行扩大培养,经IPTG诱导获得重组融合蛋白.用SDS-PAGE和Western-blotting对表达的目的蛋白进行分析.【结果】成功获得重组质粒pET-30a(+)-B2L,读码框正确.获得了43ku的表达产物,与预期目的蛋白大小相符;纯化后的目的蛋白能与ORFV阳性血清发生特异反应.【结论】成功对ORFV-B2L蛋白进行了原核表达,且纯化后蛋白具有良好的反应原性.     

Functional expression of a cloned I-A beta k gene in B-lymphoma cells

The immune response genes of the mouse encode two cell-surface glycoproteins, I-A and I-E, that play critical roles in determining the animal's immune responsiveness. The I-A antigen contains two chains, alpha and beta. A cloned beta-chain gene, I-A beta k, was introduced into B-lymphoma cells that express I-Ad. The transfected gene was successfully expressed on the cell surface of the recipient cells and was functional in stimulating allospecific T cells.     

潮霉素B抗性基因在木醋杆菌中的整合表达

以质粒pSET152为出发载体,构建潮霉素B抗性基因的表达载体pSET152-HYG,通过大肠杆菌-木醋杆菌的属间接合转移将pSET152-HYG导入木醋杆菌,在位点特异性重组酶作用下潮霉素抗性基因B整合到木醋杆菌的染色体上。与出发菌株相比,重组菌株传代稳定,潮霉素抗性有了较大的提高,从100μg/mL提高到了400μg/mL以上,而产纤维素能力只略有下降。     

鸡BMPR1B基因克隆、生物信息学及组织表达分析

[目的]探究鸡骨形态发生蛋白受体1B(bone morphogenetic protein receptor type 1B,BMPR1B)基因在家禽卵巢发育中的功能.[方法]利用cDNA末端快速扩增技术(rapid amplification of cDNA ends,RACE)扩增BM-PR1B基因cDNA的序列,...     

Hepatitis B virus DNA sequences in lymphoid cells from patients with AIDS and AIDS-related complex

A lymphotropic virus HTLV-III/LAV was recently identified as the etiologic agent of the acquired immune deficiency syndrome (AIDS). In a study of concomitant hepatitis B infections in patients with AIDS or the AIDS-related complex, DNA sequences of hepatitis B virus (HBV) were found in fresh and cultured lymphocytes from patients with AIDS even in the absence of conventional HBV serological markers. Furthermore, the restriction DNA pattern was consistent with the integration of the viral DNA. These results should prompt additional studies to reevaluate a possible role of HBV as a cofactor in AIDS in addition to the HTLV-III/LAV causal agent.     

Bone marrow-derived lymphoid cells (B cells): functional depletion with cobra factor and fresh serum

Treatment of rat spleen cells with cobra factor and fresh rat serum provided a simple, rapid means of functionally eliminating complement receptor lymphocytes. Cells able to differentiate into plaque-forming cells in a syngeneic, irradiated host were diminished, but cells able to induce a graft-versus-host reaction were not diminished. There was no effect on plaque-forming cells from an immune spleen.     

Increased insulin sensitivity and obesity resistance in mice lacking the protein tyrosine phosphatase-1B gene

Protein tyrosine phosphatase-1B (PTP-1B) has been implicated in the negative regulation of insulin signaling. Disruption of the mouse homolog of the gene encoding PTP-1B yielded healthy mice that, in the fed state, had blood glucose concentrations that were slightly lower and concentrations of circulating insulin that were one-half those of their PTP-1B+/+ littermates. The enhanced insulin sensitivity of the PTP-1B-/- mice was also evident in glucose and insulin tolerance tests. The PTP-1B-/- mice showed increased phosphorylation of the insulin receptor in liver and muscle tissue after insulin injection in comparison to PTP-1B+/+ mice. On a high-fat diet, the PTP-1B-/- and PTP-1B+/- mice were resistant to weight gain and remained insulin sensitive, whereas the PTP-1B+/+ mice rapidly gained weight and became insulin resistant. These results demonstrate that PTP-1B has a major role in modulating both insulin sensitivity and fuel metabolism, thereby establishing it as a potential therapeutic target in the treatment of type 2 diabetes and obesity.     

体外Src蛋白酪氨酸激酶抑制剂筛选模型的建立

在体外构建一个以Src蛋白为靶位点的蛋白酪氨酸激酶抑制剂快速筛选模型,为筛选Src蛋白酪氨酸激酶抑制剂奠定基础.基因工程表达GST-v-Src蛋白,收集包涵体蛋白,并经变性复性处理.以生物素化的聚Glu∶Tyr(4∶1)为激酶反应底物、以辣根过氧化物酶(horseradish peroxidase,HRP)标记的磷酸酪氨酸特异性单克隆抗体(HRP-PY20)检测磷酸酪氨酸残基的酶联免疫吸附实验(enzyme-linked immunosorbent assay,ELISA)测定获得蛋白的激酶活性,并进行抑制剂筛选.该模型具有靶向性强、快速、简便可行、高通量的特点.用该方法对6种治疗肿瘤配方中常用的中草药进行筛选,筛选出3种中草药水煎剂富含Src蛋白酪氨酸激酶抑制剂成分.     

Human apolipoprotein B: structure of carboxyl-terminal domains, sites of gene expression, and chromosomal localization

Apolipoprotein (apo-) B is the ligand responsible for the receptor-mediated catabolism of low density lipoproteins, the principal cholesterol-transporting lipoproteins in plasma. The primary structure of the carboxyl-terminal 30 percent (1455 amino acids) of human apo-B (apo-B100) has been deduced from the nucleotide sequence of complementary DNA. Portions of the protein structure that may relate to its receptor binding function and lipid binding properties have been identified. The apo-B100 messenger RNA is about 19 kilobases in length. The apo-B100 gene is expressed primarily in liver and, to a lesser extent, in small intestine, but in no other tissues. The gene for apo-B100 is located in the p24 region (near the tip of the short arm) of chromosome 2.     

Human diabetes associated with a mutation in the tyrosine kinase domain of the insulin receptor

Insulin receptor complementary DNA has been cloned from an insulin-resistant individual whose receptors have impaired tyrosine protein kinase activity. One of this individual's alleles has a mutation in which valine is substituted for Gly996, the third glycine in the conserved Gly-X-Gly-X-X-Gly motif in the putative binding site fo adenosine triphosphate. Expression of the mutant receptor by transfection into Chinese hamster ovary cells confirmed that the mutation impairs tyrosine kinase activity.