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排序方式: 共有2707条查询结果,搜索用时 218 毫秒
991.
Maria Grazia Di Certo Enrico M Batassa Ida Casella Annalucia Serafino Aristide Floridi Claudio Passananti Paola Molinari Elisabetta Mattei 《BMC cell biology》2008,9(1):56
Background
Chimeric proteins obtained by the fusion of a G protein-coupled receptor (GPCR) sequence to the N-terminus of the G protein α-subunit have been extensively used to investigate several aspects of GPCR signalling. Although both the receptor and the G protein generally maintain a fully functional state in such polypeptides, original observations made using a chimera between the β2-adrenergic receptor (β2AR) and Gαs indicated that the fusion to the α-subunit resulted in a marked reduction of receptor desensitization and down-regulation. To further investigate this phenomenon, we have compared the rates of internalization and recycling between wild-type and Gαs-fused β2AR. 相似文献992.
993.
Enrico Braidot Marco Zancani Elisa Petrussa Carlo Peresson Alberto Bertolini Sonia Patui Francesco Macrì Angelo Vianello 《Plant signaling & behavior》2008,3(9):626-632
Flavonoids are a group of secondary metabolites widely distributed in plants that represent a huge portion of the soluble phenolics present in grapevine (Vitis vinifera L.). These compounds play different physiological roles and are often involved in protection against biotic and abiotic stress. Even if the flavonoid biosynthetic pathways have been largely characterized, the mechanisms of their transport and accumulation in cell wall and vacuole are still not completely understood. This review analyses the known mechanisms of flavonoid uptake and accumulation in grapevine, with reference to the transport models and membrane carrier proteins described in other plant species. The effect of different environmental factors on flavonoid biosynthesis and transporters is also discussed.Key words: ABC proteins, active transport, bilitranslocase, biotic and abiotic stress, flavonoid, secondary metabolites 相似文献
994.
Montagnoli A Valsasina B Croci V Menichincheri M Rainoldi S Marchesi V Tibolla M Tenca P Brotherton D Albanese C Patton V Alzani R Ciavolella A Sola F Molinari A Volpi D Avanzi N Fiorentini F Cattoni M Healy S Ballinari D Pesenti E Isacchi A Moll J Bensimon A Vanotti E Santocanale C 《Nature chemical biology》2008,4(6):357-365
Cdc7 is an essential kinase that promotes DNA replication by activating origins of replication. Here, we characterized the potent Cdc7 inhibitor PHA-767491 (1) in biochemical and cell-based assays, and we tested its antitumor activity in rodents. We found that the compound blocks DNA synthesis and affects the phosphorylation of the replicative DNA helicase at Cdc7-dependent phosphorylation sites. Unlike current DNA synthesis inhibitors, PHA-767491 prevents the activation of replication origins but does not impede replication fork progression, and it does not trigger a sustained DNA damage response. Treatment with PHA-767491 results in apoptotic cell death in multiple cancer cell types and tumor growth inhibition in preclinical cancer models. To our knowledge, PHA-767491 is the first molecule that directly affects the mechanisms controlling initiation as opposed to elongation in DNA replication, and its activities suggest that Cdc7 kinase inhibition could be a new strategy for the development of anticancer therapeutics. 相似文献
995.
Fogli M Mavilio D Brunetta E Varchetta S Ata K Roby G Kovacs C Follmann D Pende D Ward J Barker E Marcenaro E Moretta A Fauci AS 《PLoS pathogens》2008,4(7):e1000101
Understanding the cellular mechanisms that ensure an appropriate innate immune response against viral pathogens is an important challenge of biomedical research. In vitro studies have shown that natural killer (NK) cells purified from healthy donors can kill heterologous cell lines or autologous CD4+ T cell blasts exogenously infected with several strains of HIV-1. However, it is not known whether the deleterious effects of high HIV-1 viremia interferes with the NK cell-mediated cytolysis of autologous, endogenously HIV-1-infected CD4+ T cells. Here, we stimulate primary CD4+ T cells, purified ex vivo from HIV-1-infected viremic patients, with PHA and rIL2 (with or without rIL-7). This experimental procedure allows for the significant expansion and isolation of endogenously infected CD4+ T cell blasts detected by intracellular staining of p24 HIV-1 core antigen. We show that, subsequent to the selective down-modulation of MHC class-I (MHC-I) molecules, HIV-1-infected p24(pos) blasts become partially susceptible to lysis by rIL-2-activated NK cells, while uninfected p24(neg) blasts are spared from killing. This NK cell-mediated killing occurs mainly through the NKG2D activation pathway. However, the degree of NK cell cytolytic activity against autologous, endogenously HIV-1-infected CD4+ T cell blasts that down-modulate HLA-A and -B alleles and against heterologous MHC-I(neg) cell lines is particularly low. This phenomenon is associated with the defective surface expression and engagement of natural cytotoxicity receptors (NCRs) and with the high frequency of the anergic CD56(neg)/CD16(pos) subsets of highly dysfunctional NK cells from HIV-1-infected viremic patients. Collectively, our data demonstrate that the chronic viral replication of HIV-1 in infected individuals results in several phenotypic and functional aberrancies that interfere with the NK cell-mediated killing of autologous p24(pos) blasts derived from primary T cells. 相似文献
996.
Chloroplast movement as a response of plants to light variations is presented as an example in each classical textbook, showing that these organelles accumulate in response to low light and avoid high light irradiation. In sharp contrast to the morphological discovery of the phenomenon, which dates back more than a century, the molecular understanding of this effect is just at its beginning and only recently first components of the signal cascade initiating this process were described. Among these, a protein termed CHUP1 was identified. This protein is present in the outer membrane of chloroplasts and thereby discussed as the first component of a possible ‘moving ensemble’ assembling at the ‘moved cargo’. The protein is able to interact with actin and profilin—and even more, is able to regulate this interaction in vitro. Thereby, today it can be stated that actin filament reformation and chloroplast repositioning are coordinated if not dependent on each other.Key words: chloroplast movement, profilin binding, actin binding, avoidance response of chloroplasts 相似文献
997.
Luca Pasini Maria Rosaria Stile Enrico Puja Rita Valsecchi Priscilla Francia Giorgia Carletti Francesco Salamini Adriano Marocco 《Molecular breeding : new strategies in plant improvement》2008,22(4):527-541
In this paper, 10 mutations conditioning the appearance of defective, miniature or collapsed endosperm, but with normal sporophyte
development, were considered. Homozygous mutant kernels have reduced grain weight, kernel size, density and, in some of these,
higher than normal seed protein content. The mutant loci were integrated into a high-resolution genetic map in order to associate
them to specific genes. We have placed 1167 AFLP markers on a consensus map using IBM2 as a backbone and reaching an average
of 1 marker every 1.9 cM. We have identified AFLP markers linked to all individual mutant alleles. BSA was adopted to screen
the largest possible number of primer combinations on homozygous F3 mutant and wild type plants. The ten mutant loci are linked to the closest AFLP or SSR markers with distances ranging from
0 to 17.9 cM. The genes we have defined by the existence of mendelian mutants can now be considered good candidates for testing
the association to QT loci.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
998.
999.
1000.
The plastid outer membrane localized LPTD1 is important for glycerolipid remodelling under phosphate starvation
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Glycerolipid synthesis in plants is coordinated between plastids and the endoplasmic reticulum (ER). A central step within the glycerolipid synthesis is the transport of phosphatidic acid from ER to chloroplasts. The chloroplast outer envelope protein TGD4 belongs to the LptD family conserved in bacteria and plants and selectively binds and may transport phosphatidic acid. We describe a second LptD‐family protein in A. thaliana (atLPTD1; At2g44640) characterized by a barrel domain with an amino‐acid signature typical for cyanobacterial LptDs. It forms a cation selective channel in vitro with a diameter of about 9 Å. atLPTD1 levels are induced under phosphate starvation. Plants expressing an RNAi construct against atLPTD1 show a growth phenotype under normal conditions. Expressing the RNAi against atLPTD1 in the tgd4–1 background renders the plants more sensitive to light stress or phosphate limitation than the individual mutants. Moreover, lipid analysis revealed that digalactosyldiacylglycerol and sulfoquinovosyldiacylglycerol levels remain constant in the RNAi mutants under phosphate starvation, while these two lipids are enhanced in wild‐type. Based on our results, we propose a function of atLPTD1 in the transport of lipids from ER to chloroplast under phosphate starvation, which is combinatory with the function of TGD4. 相似文献