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1.
Cell cycle control of DNA replication by a homologue from human cells of the p34cdc2 protein kinase 总被引：52，自引：0，他引：52
The regulation of DNA replication during the eukaryotic cell cycle was studied in a system where cell free replication of simian virus 40 (SV40) DNA was used as a model for chromosome replication. A factor, RF-S, was partially purified from human S phase cells based on its ability to activate DNA replication in extracts from G1 cells. RF-S contained a human homologue of the Schizosaccharomyces pombe p34cdc2 kinase, and this kinase was necessary for RF-S activity. The limiting step in activation of the p34 kinase at the G1 to S transition may be its association with a cyclin since addition of cyclin A to a G1 extract was sufficient to start DNA replication. These observations suggest that the role of p34cdc2 in controlling the start of DNA synthesis has been conserved in evolution. 相似文献
2.
cdc2 gene expression at the G1 to S transition in human T lymphocytes 总被引：39，自引：0，他引：39
Y Furukawa H Piwnica-Worms T J Ernst Y Kanakura J D Griffin 《Science (New York, N.Y.)》1990,250(4982):805-808
The product of the cdc2 gene, designated p34cdc2, is a serine-threonine protein kinase that controls entry of eukaryotic cells into mitosis. Freshly isolated human T lymphocytes (G0 phase) were found to have very low amounts of p34cdc2 and cdc2 messenger RNA. Expression of cdc2 increased 18 to 24 hours after exposure of T cells to phytohemagglutinin, coincident with the G1 to S transition. Antisense oligodeoxynucleotides could reduce the increase in cdc2 expression and inhibited DNA synthesis, but had no effect on several early and mid-G1 events, including blastogenesis and expression of interleukin-2 receptors, transferrin receptors, c-myb, and c-myc. Induction of cdc2 required prior induction of c-myb and c-myc. These results suggest that cdc2 induction is part of an orderly sequence of events that occurs at the G1 to S transition in T cells. 相似文献
3.
目的探讨P34cdc2、CyclinB1和Survivin在鼻咽粘膜慢性炎、鼻咽癌和颈部淋巴结转移灶中的表达及意义,并分析与EBV-LMP1表达的相互关系.方法应用免疫组化检测30例鼻咽粘膜慢性炎、30例鼻咽癌和30例鼻咽癌颈部淋巴结转移灶中LMP1、P34cdc2、CyclinB1和Survivin的表达.结果LMP1、P34cdc2、CyclinB1和Survivin在鼻咽粘膜慢性炎中的阳性率分别为20.0%(6/30)、10.0%(3/30)、10.0%(3/30)和3.3%(1/30);在鼻咽癌中的阳性率分别为63.3%(19/30)、73.3%(22/30)、50.0%(15/30)和36.7(11/30),与鼻咽粘膜慢性炎比较差异均有显著性(P＜0.01);在鼻咽癌颈部淋巴结转移灶中的阳性率分别为70.0%(21/30)、80.0%(24/30)、76.7%(23/30)和43.3%(13/30),与鼻咽粘膜慢性炎比较差异均有显著性(P＜0.01),与鼻咽癌相比较均有所增高,但仅CyclinB1有统计学意义(P＜0.05).在鼻咽癌及其颈部淋巴结转移灶中,LMP1与P34cdc2和CyclinB1的表达均有显著相关性(分别P＜0.01,P＜0.05).结论鼻咽癌中存在P34cdc2、CyclinB1和Survivin蛋白过表达,LMP1与P34cdc2和CyclinB1可能协同致病. 相似文献
4.
Inhibition of lymphocyte proliferation by a synthetic peptide homologous to retroviral envelope proteins 总被引：47，自引：0，他引：47
The retroviral transmembrane envelope protein p15E is immunosuppressive in that it inhibits immune responses of lymphocytes, monocytes, and macrophages. A region of p15E has been conserved among murine and feline retroviruses; a homologous region is also found in the transmembrane envelope proteins of the human retroviruses HTLV-I and HTLV-II and in a putative envelope protein encoded by an endogenous C-type human retroviral DNA. A peptide (CKS-17) was synthesized to correspond to this region of homology and was examined for its effects on lymphocyte proliferation. CKS-17 inhibited the proliferation of an interleukin-2-dependent murine cytotoxic T-cell line as well as alloantigen-stimulated proliferation of murine and human lymphocytes. Four other peptides, representing different regions of virus proteins, were inactive. These results suggest that the immunosuppressive portion of retroviral transmembrane envelope proteins may reside, at least in part, in a-conserved sequence represented by the CKS-17 peptide. 相似文献
5.
通过RT-PCR从CMV和ToMV新疆分离物中扩增出CMV 2b和ToMVCP这2个基因,按正确方向将目标片段分别插入诱饵载pSos中,并将重组质粒导入酵母温度敏感酵母菌株cdc25H,检测其表达产物对酵母Sos恢复系统Ras信号通路的激活作用和对酵母细胞温敏特性影响。结果表明,这2个诱饵载体构建成功,对酵母菌株cdc25H无毒性和对Sos恢复系统无激活作用。为利用酵母双杂交系统研究加工番茄病毒的感染机制和病毒-寄主相互作用及防治加工番茄病毒病奠定了基础。 相似文献
6.
Vig M Peinelt C Beck A Koomoa DL Rabah D Koblan-Huberson M Kraft S Turner H Fleig A Penner R Kinet JP 《Science (New York, N.Y.)》2006,312(5777):1220-1223
Store-operated Ca2+ entry is mediated by Ca2+ release-activated Ca2+ (CRAC) channels following Ca2+ release from intracellular stores. We performed a genome-wide RNA interference (RNAi) screen in Drosophila cells to identify proteins that inhibit store-operated Ca2+ influx. A secondary patch-clamp screen identified CRACM1 and CRACM2 (CRAC modulators 1 and 2) as modulators of Drosophila CRAC currents. We characterized the human ortholog of CRACM1, a plasma membrane-resident protein encoded by gene FLJ14466. Although overexpression of CRACM1 did not affect CRAC currents, RNAi-mediated knockdown disrupted its activation. CRACM1 could be the CRAC channel itself, a subunit of it, or a component of the CRAC signaling machinery. 相似文献
7.
In Saccharomyces cerevisiae, the telomerase components Est2p, TLC1 RNA, Est1p, and Est3p are thought to form a complex that acts late during chromosome replication (S phase) upon recruitment by Cdc13p, a telomeric DNA binding protein. Consistent with this model, we show that Est1p, Est2p, and Cdc13p are telomere-associated at this time. However, Est2p, but not Est1p, also binds telomeres before late S phase. The cdc13-2 allele has been proposed to be defective in recruitment, yet Est1p and Est2p telomere association persists in cdc13-2 cells. These findings suggest a model in which Est1p binds telomeres late in S phase and interacts with Cdc13p to convert inactive, telomere-bound Est2p to an active form. 相似文献
8.
9.
Signaling by guanine nucleotide-binding proteins (G proteins) involves sequential protein-protein interactions. G protein-betagamma subunit (Gbetagamma) interactions with phospholipase C-beta2 (PLC-beta2) were studied to determine if all Gbeta contacts are required for signaling. A peptide encoding Gbeta amino acid residues 86 to 105 stimulated PLC-beta2. Six residues (96 to 101) within this sequence could transfer signals and thus constitute a core signal transfer region. Another peptide, encoding Gbeta amino acid residues 115 to 135, did not substantially stimulate PLC-beta2 by itself but inhibited Gbetagamma stimulation, indicating that residues 115 to 135 constitute a general binding domain. Resolution of signal transfer regions from general binding domains indicates that all protein-protein contacts are not required for signal transfer and that it may be feasible to synthesize agonists and antagonists that regulate intracellular signal flow. 相似文献
10.
The effects of various Ca^2 -modifying drugs on moue egg fertilization were studied.Ca^2 chelator,ethylen glycol-bis-(2-aminoethyl)-tetracetic acid(EGTA),and calmodulin(CaM) antagonist,trifluoperzaine (TFP),inhibited fertilization in a dose-dependent manner,whild Ca^2 channel bolcker,verspamil,did not have any effect.When intracellular Ca^2 release was blocked by 8-(N,N-diethylamino) octy 1-3,4,5-trimethoxy-benzonate(TME-8) or the Ca^2 oscillations were inhibited by an inhibitor of endoplasmic reticulum Ca^2 -At-Pase,thapsigargin,the second polar body emission and pronuclear formation were significantly decreased.In contrast,inhibition of intracellular Ca^2 release via bolckage of inositol 1,4,5-triphosphate (IP3) production by neomycin or lithium did not affect fertilization.The results sugest that both extracellular influx,intracellular Ca^2 release and CaM activation are required for mormal fertilization.However,extracellular influx through voltage-gated Ca^2 channel and intracellular release induced by IP3 and not the only pathways for producing Ca^2 transients in moue eggs. 相似文献
11.
Sano Y Inamura K Miyake A Mochizuki S Yokoi H Matsushime H Furuichi K 《Science (New York, N.Y.)》2001,293(5533):1327-1330
We characterized an activation mechanism of the human LTRPC2 protein, a member of the transient receptor potential family of ion channels, and demonstrated that LTRPC2 mediates Ca2+ influx into immunocytes. Intracellular pyrimidine nucleotides, adenosine 5'-diphosphoribose (ADPR), and nicotinamide adenine dinucleotide (NAD), directly activated LTRPC2, which functioned as a Ca2+-permeable nonselective cation channel and enabled Ca2+ influx into cells. This activation was suppressed by intracellular adenosine triphosphate. These results reveal that ADPR and NAD act as intracellular messengers and may have an important role in Ca2+ influx by activating LTRPC2 in immunocytes. 相似文献
12.
Interleukin-8 (IL-8) is an inflammatory cytokine that activates neutrophil chemotaxis, degranulation, and the respiratory burst. Neutrophils express receptors for IL-8 that are coupled to guanine nucleotide-binding proteins (G proteins); binding of IL-8 to its receptor induces the mobilization of intracellular calcium stores. A cDNA clone from HL-60 neutrophils, designated p2, has now been isolated that encodes a human IL-8 receptor. When p2 is expressed in oocytes from Xenopus laevis, the oocytes bind 125I-labeled IL-8 specifically and respond to IL-8 by mobilizing calcium stores with an EC50 of 20 nM. This IL-8 receptor has 77% amino acid identity with a second human neutrophil receptor isotype that binds IL-8 with higher affinity. It also exhibits 69% amino acid identity with a protein reported to be an N-formyl peptide receptor from rabbit neutrophils, but less than 30% identity with all other known G protein-coupled receptors, including the human N-formyl peptide receptor. 相似文献
13.
Induction by NGF of meiotic maturation of Xenopus oocytes expressing the trk proto-oncogene product. 总被引：16，自引：0，他引：16
A R Nebreda D Martin-Zanca D R Kaplan L F Parada E Santos 《Science (New York, N.Y.)》1991,252(5005):558-561
The effect of nerve growth factor (NGF) was assessed in Xenopus oocytes expressing the human trk proto-oncogene product, p140prototrk. Oocytes injected with trk messenger RNA expressed polypeptides recognized by antibodies to the trk gene product. Exposure of these oocytes to nanomolar amounts of NGF resulted in specific surface binding of 125I-labeled NGF, tyrosine phosphorylation of p140prototrk, and meiotic maturation, as determined by germinal vesicle breakdown and maturation promoting factor (p34cdc2) kinase activation. Thus the trk proto-oncogene product can act as a receptor for NGF in a functionally productive manner. 相似文献
14.
植物中的Δ12脂肪酸脱氢酶(FAD2)是油酸形成亚油酸的关键酶。通过NCBI和EXPASY 2大数据库,采用Signal P、TMHMM、Psort、Prot Param和Target P等分析程序对花生品种‘航花2号’及其它物种的19个FAD2蛋白序列进行分析,利用MEGA6.0软件比对序列及构建系统进化树阐明FAD2基因的系统发育关系,亲缘相近的FAD2蛋白聚在一起。预测了‘航花2号’和‘粤油13’的FAD2蛋白的分子质量、等电点、信号肽、跨膜和保守结构域等。结果表明:‘航花2号’FAD2蛋白的N端没有信号肽,预测定位在微体、细胞质、线粒体基质和叶绿体类囊膜中,而C端信号基序LKGL使得FAD2蛋白选择性地结合和嵌入内质网,植物的FAD2蛋白普遍有3个高度保守的组氨酸富集基序(HECGHH、HRRHH和H[A/C/T]HH)和3~5个跨膜结构,但分析结果显示,‘航花2号’的FAD2蛋白的H[A/C/T]HH的组氨酸基序是缺失的,而油酸转化为亚油酸的效率上并没有显著变化,为将来FAD2基因的基因工程操作提供一定的理论基础。 相似文献
15.
Structure of a peptide inhibitor bound to the catalytic subunit of cyclic adenosine monophosphate-dependent protein kinase 总被引：69，自引：0，他引：69
D R Knighton J H Zheng L F Ten Eyck N H Xuong S S Taylor J M Sowadski 《Science (New York, N.Y.)》1991,253(5018):414-420
The structure of a 20-amino acid peptide inhibitor bound to the catalytic subunit of cyclic AMP-dependent protein kinase, and its interactions with the enzyme, are described. The x-ray crystal structure of the complex is the basis of the analysis. The peptide inhibitor, derived from a naturally occurring heat-stable protein kinase inhibitor, contains an amphipathic helix that is followed by a turn and an extended conformation. The extended region occupies the cleft between the two lobes of the enzyme and contains a five-residue consensus recognition sequence common to all substrates and peptide inhibitors of the catalytic subunit. The helical portion of the peptide binds to a hydrophobic groove and conveys high affinity binding. Loops from both domains converge at the active site and contribute to a network of conserved residues at the sites of magnesium adenosine triphosphate binding and catalysis. Amino acids associated with peptide recognition, nonconserved, extend over a large surface area. 相似文献
16.
Inositol 1,4,5-trisphosphate [I(1,4,5)P3] is a second messenger generated along with diacylglycerol upon the binding of various physiological agents with their cell surface receptors. I(1,4,5)P3 mobilizes Ca2+ from intracellular storage sites through a receptor-coupled mechanism, and the subsequent increased intracellular free calcium ion concentration [( Ca2+]i) activates a multitude of cellular responses. Electropermeabilized neoplastic rat liver epithelial (261B) cells were used to study Ca2+ sequestration, a process that reverses the elevated [Ca2+]i to resting levels and replenishes intracellular Ca2+ pools. Although I (1,4,5)P3-mobilized Ca2+ is readily sequestered into storage pools by the action of Ca2+-adenosine triphosphatases, Ca2+ mobilized by addition of the nonmetabolized inositol trisphosphate isomer I(2,4,5)P3 is not sequestered, suggesting that metabolism is necessary to eliminate the stimulus for Ca2+ release. Several inositol phosphate compounds were examined for their ability to lower the buffer [Ca2+] to determine if a specific I(1,4,5)P3 metabolite might be involved in stimulating Ca2+ sequestration; of these, I(1,3,4,5)P4 alone was found to induce Ca2+ sequestration, demonstrating a physiological role for this inositol trisphosphate metabolite. 相似文献
17.
18.
DONG Shi-shan WANG Ying-chun MALi-qin LI Kai ZHANG Jian-jun OU De-yuan ZHAO Li-hong LIU Ju-xiang QIAO Jian 《中国农业科学(英文版)》2007,6(9):1133-1137
The purpose of this research was to study the effect of hypoxia on the Ca^2＋ concentration in broiler＇s cardiac muscle cells （CMCs）. The concentration of Ca^2＋ in the CMC was observed using a laser scanning confocal microscope （LSCM）. The results showed that hypoxia could significantly increase intracellular Ca^2＋（normal oxygen, 99.3 ＋_ 13.1; hypoxia, 129.4 ＋_ 24.3, P 〈 0.01） in CMCs. The Ca^2＋ antagonist （nifedipine, verapamil） could significantly restrain the Ca^2＋ influx across the cell membrane of CMC treated by hypoxia （CMC： hypoxia ＋ verapamil, 100.9± 28.2; hypoxia ＋ nifedipine, 107.6± 27.7; P 〈 0.01）. The results showed hypoxia could increase intracellular Ca^2＋ concentration of CMC, and the Ca^2＋ antagonist could restrain the Ca^2＋ influx across the cell membrane of CMC treated by hypoxia. 相似文献
19.
野生大豆CDPK基因保守区的克隆及序列分析 总被引：5，自引：0，他引：5
CDPK(Ca2+-dependent,calmodulinindependentproteinkinase)是植物钙信号传导过程中关键的蛋白激酶,在逆境胁迫信号传导过程中起到重要作用。研究基于同源序列候选基因的策略,根据已经公布的多个CDPK序列的比对结果,在保守性较高的区域,设计两对巢式简并引物,结合降落PCR和巢式PCR在野生大豆中克隆。对获得的序列片段进行序列分析,发现该序列具有激酶活性的功能区域和CDPK特有的EF手性结构区,并且与VrCDPK(U08140)序列达到94%的相似性,可以确定该片段是CDPK基因的保守序列。结果证明,野生大豆中也存在CDPK基因,并为通过RACE等方法获得野生大豆全长CDPK基因奠定了基础。 相似文献
20.
Ca(2+)-induced Ca2+ release in sea urchin egg homogenates: modulation by cyclic ADP-ribose 总被引：19，自引：0，他引：19
Calcium-induced calcium release (CICR) may function widely in calcium-mediated cell signaling, but has been most thoroughly characterized in muscle cells. In a homogenate of sea urchin eggs, which display transients in the intracellular free calcium concentration ([Ca2+]i) during fertilization and anaphase, addition of Ca2+ triggered CICR. Ca2+ release was also induced by the CICR modulators ryanodine and caffeine. Responses to both Ca2+ and CICR modulators (but not Ca2+ release mediated by inositol 1,4,5-trisphosphate) were inhibited by procaine and ruthenium red, inhibitors of CICR. Intact eggs also displayed transients of [Ca2+]i when microinjected with ryanodine. Cyclic ADP-ribose, a metabolite with potent Ca(2+)-releasing properties, appears to act by way of the CICR mechanism and may thus be an endogenous modulator of CICR. A CICR mechanism is present in these nonmuscle cells as is assumed in various models of intracellular Ca2+ wave propagation. 相似文献