Identification and location of brain protein 4.1

Protein 4.1 is a membrane skeletal protein that converts the low-affinity interaction between spectrin and actin into a high-affinity ternary complex of spectrin, protein 4.1, and actin that is essential to the structural stability of the erythrocyte. Pig brain was shown to contain an 87-kilodalton immunoreactive analog of protein 4.1 that has partial sequence homology with pig erythrocyte protein 4.1 and the same location as spectrin in the cortical cytoplasm of neuronal and glial cell types of the cerebellum.     

Oligodendrocyte adhesion activates protein kinase C-mediated phosphorylation of myelin basic protein

When isolated adult oligodendrocytes adhere to a substratum myelinogenesis occurs. Investigation of the mechanism by which this happens indicated that the oligodendrocyte-substratum interaction activated protein kinase C-dependent phosphorylation of myelin basic protein and promoted the synthesis of myelin basic protein. In addition, when agents that activate protein kinase C (second messenger diacylglycerol or a tumor-promoting phorbol ester) were added to nonattached oligodendrocytes, they mimicked the influence of the substratum by inducing phosphorylation of myelin basic protein; and reagents that increase cellular adenosine 3', 5'-monophosphate (cyclic AMP) inhibited phosphorylation of myelin basic protein. Thus, at least in vitro, the interaction between oligodendrocytes and the substratum may mediate myelinogenic events, and phosphorylation of myelin basic protein may be an early requirement in the sequence of steps that ultimately results in myelin formation.     

猪圆环病毒2型Cap蛋白的原核表达及其抗原性分析

根据GenBank中登录的PCV-2序列,设计1对特异性引物,PCR扩增PCV-2去除核定位信号(nuclear localization signal,NLS)的Cap蛋白基因,经Bam HI和Xho I双酶切后将其插入到表达载体pEGX-4T-1多克隆位点,并转化到表达菌株Rossetta(DM3)中,采用IPTG进行诱导表达,采用SDS-PAGE薄层灰度分析表达情况,收集菌体,使用GST-Protein Purification Kit亲和层析纯化方法对表达的GST-Cap融合蛋白蛋白进行纯化,SDS-PAGE电泳检测纯化效果,Western blot分析纯化后的重组Cap蛋白(rCap)免疫学活性。结果表明,成功克隆了大小为579 bp去除核定位信号的ORF2基因,成功诱导表达出预期大小45.3 ku相一致的rCap蛋白,表达量占总菌体的25%,纯化后的rCap蛋白SDS-PAGE电泳分析纯度达到90%以上,Western blot分析表明纯化的rCap蛋白能与PCV-2阳性血清发生特异性反应,具有良好的免疫学活性。     

Nitrogenase complexes: multiple docking sites for a nucleotide switch protein

Adenosine triphosphate (ATP) hydrolysis in the nitrogenase complex controls the cycle of association and dissociation between the electron donor adenosine triphosphatase (ATPase) (Fe-protein) and its target catalytic protein (MoFe-protein), driving the reduction of dinitrogen into ammonia. Crystal structures in different nucleotide states have been determined that identify conformational changes in the nitrogenase complex during ATP turnover. These structures reveal distinct and mutually exclusive interaction sites on the MoFe-protein surface that are selectively populated, depending on the Fe-protein nucleotide state. A consequence of these different docking geometries is that the distance between redox cofactors, a critical determinant of the intermolecular electron transfer rate, is coupled to the nucleotide state. More generally, stabilization of distinct docking geometries by different nucleotide states, as seen for nitrogenase, could enable nucleotide hydrolysis to drive the relative motion of protein partners in molecular motors and other systems.     

Macrophage ribonucleoprotein: nature of the antigenic fragment

The antigenic fragments of bacteriophage T2 recovered in RNA derived from macrophages infected with T2 bacteriophage retain their capacity to combine with specific neutralizing antibody to T2. The preservation of the complete native tertiary structure of tail fiber antigen of bacteriophage T2 is not requiired for immucnogenicity.     

Partial characterization of 21.5K myelin basic protein from sheep brain

The 21,500 molecular weight (21.5K) variant of myelin basic protein (MBP) was isolated from sheep brain and partially characterized. Digestion with cyanogen bromide and trypsin yielded peptides which showed that approximately 30 additional amino acids were inserted at the equivalent of the amino acid at position 57 in the bovine 18.5K MBP sequence. An unusually hydrophobic peptide Pro, Val, Leu, Trp, Lys was present in this region. Ornithine was present in hydrolyzates of 21.5K MBP, but it was not detected in any of the peptides.     

Amino acid homology between the encephalitogenic site of myelin basic protein and virus: mechanism for autoimmunity

Amino acid sequence homology was found between viral and host encephalitogenic protein. Immune responses were then generated in rabbits by using the viral peptide that cross-reacts with the self protein. Mononuclear cell infiltration was observed in the central nervous systems of animals immunized with the viral peptide. Myelin basic protein (MBP) is a host protein whose encephalitogenic site of ten amino acids induces experimental allergic encephalomyelitis. By computer analysis, hepatitis B virus polymerase (HBVP) was found to share six consecutive amino acids with the encephalitogenic site of rabbit MBP. Rabbits given injections of a selected eight- or ten-amino acid peptide from HBVP made antibody that reacted with the predetermined sequences of HBVP and also with native MBP. Peripheral blood mononuclear cells from the immunized rabbits proliferated when incubated with either MBP or HBVP. Central nervous system tissue taken from these rabbits had a histologic picture reminiscent of experimental allergic encephalomyelitis. Thus, viral infection may trigger the production of antibodies and mononuclear cells that cross-react with self proteins by a mechanism termed molecular mimicry. Tissue injury from the resultant autoallergic event can take place in the absence of the infectious virus that initiated the immune response.     

NDV F48E9株与LaSota株HN结构蛋白潜在抗原表位的预测分析

该文阐述了以新城疫病毒F48E9株和LaSota株HN结构蛋白的氨基酸序列为依据,先采用Chou—Fasman方法、Garnier—Robson方法、Emini方法、Kyte-Doolittle方法和Karplus—Schulz方法分别预测HN蛋白的二级结构、表面可能性、亲水性和柔韧性,单参数分析HN蛋白的结构和性质,再通过Jameson—Wolf方法,综合不同的参数评价HN蛋白各个部位的抗原性,预测分析结果表明,将各参数综合考虑,能显著提高预测准确度。     

Autophosphorylation of protein kinase C at three separated regions of its primary sequence

The major autophosphorylation sites of the rat beta II isozyme of protein kinase C were identified. The modified threonine and serine residues were found in the amino-terminal peptide, the carboxyl-terminal tail, and the hinge region between the regulatory lipid-binding domain and the catalytic kinase domain. Because this autophosphorylation follows an intrapeptide mechanism, extraordinary flexibility of the protein is necessary to phosphorylate the three regions. Comparison of the sequences surrounding the modified residues showed no obvious recognition motif nor any similarity to substrate phosphorylation sites, suggesting that proximity to the active site may be the primary criterion for their phosphorylation.     

Human leukocyte antigenic specificity HL-A3: frequency of occurrence

Reactivity of antiserum against HL-A3, a human leukocyte and tissue antigenic specificity, depends upon a property of the lymphocyte as well as on the potency of the serum. Many reactions of HL-A3 antiserums can only be recognized through absorption or by a two-stage test not in general use. Interpretations of donor-recipient compatibility and of the constitution of HL-A alleles affected by these findings.     

新城疫病毒F蛋白结构域基因原核表达与抗原表位分析

以含新城疫病毒(NDV)融合蛋白(F)基因的重组质粒为模板,设计特异引物进行重叠-延伸PCR扩增获得F基因的抗原结构域基因片段Fa、Fb和Fa-l-Fb,经SalⅠ和NotⅠ酶切后,定向插入原核表达载体pGEX-6P-1,获得重组质粒pGEX-Fa、pGEX-Fb和pGEX-Fa-l-Fb;用定点突变方法获得重组质粒pGEX-Fa-mut.将重组质粒转化大肠杆菌BL21,转化菌经IPTG诱导、提取表达产物进行蛋白电泳和免疫印迹分析.结果表明:Fa-mut、Fb和Fa-l-Fb结构域基因均获得了融合表达,表达产物与NDV阳性血清具有免疫反应性;与pGEX-Fa-mut不同,pGEX-Fa重组质粒在大肠杆菌中未能表达,且转化菌在IPTG诱导过程中未见生长,提示未经突变的Fa片段可能为毒性蛋白.三维结构预测结果显示,目的蛋白片段中均保留F蛋白中原有相应的抗原表位.     

Accumulation characteristic of protein bodies in different regions of wheat endosperm under drought stress

The structural characteristics of protein body accumulation in different endosperm regions of hard wheat cultivar(XM33) and soft wheat cultivar(NM13) under drought stress were investigated. Drought stress treatment was implemented from plant regreening to the caryopsis mature stage. Microscope images of endosperm cells were obtained using resin semithin slice technology to observe the distribution and relative area of protein body(PB). Compared with NM13, relative PB area of XM33 was significantly higher in sub-aleurone endosperm region. The amount of accumulation, including the size and relative area of PB, in two wheat cultivars was higher in sub-aleurone region than that in central region at 18 days post anthesis(DPA). Drought stress significantly enhanced the sizes and relative areas of PBs in the dorsal and abdominal endosperms in two wheat cultivars. Particularly for dorsal endosperm, drought stress enhanced the relative PB area at 18 DPA and NM13(5.0% vs. 6.73%) showed less enhancement than XM33(5.49% vs. 8.96%). However, NM13(9.58% vs. 12.02%) showed greater enhancement than XM33(10.25% vs. 11.7%) at 28 DPA. The protein content in the dorsal and abdominal endosperms of the two wheat cultivars decreased at 12 DPA and then increased until 38 DPA. Drought stress significantly increased the protein contents in the two main regions. From 12 to 38 DPA, the amount of PB accumulation and the protein content were higher in XM33 than those in NM13. The results revealed that PB distribution varied in different endosperm tissues and that the amount of PB accumulation was remarkably augmented by drought stress.     

丁香假单胞大豆致病变种不同HrpZ蛋白差异区域功能研究

[目的]丁香假单胞大豆致病变种(Pseudomonas syringae pv.glycinea)A1和S1菌株编码产生的Hrp Z蛋白差异序列主要集中在C端的3个区域,并且这2个蛋白诱导非寄主HR的能力也存在差异。本研究将探究Hrp Z蛋白这3个差异区域在烟草上诱导HR(hypersensitive response)和抑制烟草花叶病毒(TMV)中所起的作用。[方法]采用常规PCR及重叠PCR方法将这2个hrp Z基因的3个差异区域分别进行互换,构建了相应的重组表达载体,表达并纯化得到了6个重组蛋白,相对分子质量均在41×103左右。并检测了其诱导HR活性、诱导植物抗病性。[结果]检测结果表明:重组蛋白Hrp ZS(S2→A2)和Hrp ZA(A3→S3)诱导HR的能力相比亲本都有所增强,6个重组蛋白诱导烟草抗TMV的活性都明显强于亲本,其中,Hrp ZA(A3→S3)和Hrp ZS(S3→A3)的活性最强。[结论]此试验表明Hrp Z蛋白的这些差异区域(第7、8、9个α-螺旋)是过敏反应能力的主要调控区域,同时C-端第8、9个α-螺旋区域与诱导植物抗病性也显著相关。本研究为改造Hrp Z类harpin蛋白激发子,提高其诱导抗性及功能域研究提供了理论依据。     

不同产地芡实种仁中蛋白质与 淀粉组分差异性研究

以4个不同产地的芡实(Euryale ferox Salisb.)为试验材料,对其种仁中主要营养成分如蛋白质、淀粉组分进行了分析测定.结果表明,芡实种仁蛋白质主要由清蛋白、球蛋白、醇溶蛋白和谷蛋白构成;不同产地芡实的总蛋白质含量无显著差异,但4种不同蛋白的含量存在显著差异,其中3号芡实的清蛋白和球蛋白含量最高、醇溶蛋白和谷蛋白含量最低,1号芡实的醇溶蛋白和谷蛋白含量最高、清蛋白和球蛋白含量最低.SDS-PAGE图谱分析表明,4种不同产地的芡实均在45.0～66.2 kD处均含有一条明显的蛋白谱带,而3号芡实在20～45 kD范围内含3条明显蛋白谱带,表明3号芡实含有更多类型的蛋白组分或同工酶成分.此外,不同产地芡实种仁的直链淀粉和支链淀粉含量比值差异显著,其中2号芡实的支链淀粉含量最高,3号芡实支链淀粉含量最低.     

Conversion of normal behavior to shiverer by myelin basic protein antisense cDNA in transgenic mice

Myelin basic proteins (MBPs) are coded by the single gene necessary for myelin formation in the central nervous system of the mouse. An antisense MBP mini-gene was constructed and used to determine the function of antisense DNA in transgenic mice. Several transgenic offspring of a founder transgenic mouse, AS100, were converted from the normal to mutant shiverer phenotype. Antisense MBP messenger RNA was expressed in these mice, and the endogenous MBP messenger RNA, the MBP, and the myelination in the central nervous system were reduced.     

Nucleotide sequence of a bovine clone encoding the angiogenic protein, basic fibroblast growth factor

Basic and acidic fibroblast growth factors (FGF's) are potent mitogens for capillary endothelial cells in vitro, stimulate angiogenesis in vivo, and may participate in tissue repair. An oligonucleotide probe for bovine basic FGF was designed from the nucleotide sequence of the amino-terminal exon of bovine acidic FGF, taking into account the 55 percent amino acid sequence homology between the two factors. With this oligonucleotide probe, a full length complementary DNA for basic FGF was isolated from bovine pituitary. Basic FGF in bovine hypothalamus was shown to be encoded by a single 5.0-kilobase messenger RNA; in a human hepatoma cell line, both 4.6- and 2.2-kilobase basic FGF messenger RNA's were present. Both growth factors seem to be synthesized with short amino-terminal extensions that are not found on the isolated forms for which the amino acid sequences have been determined. Neither basic nor acidic FGF has a classic signal peptide.     

The effects of soil properties,cropping systems and geographic location on soil prokaryotic communities in four maize production regions across China

The diversity of prokaryotic communities in soil is shaped by both biotic and abiotic factors. However, little is known about the major factors shaping soil prokaryotic communities at a large scale in agroecosystems. To this end, we undertook a study to investigate the impact of maize production cropping systems, soil properties and geographic location(latitude and longitude) on soil prokaryotic communities using metagenomic techniques, across four distinct maize production regions in China. Acr...