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971.
Kefala G Kwiatkowski W Esquivies L Maslennikov I Choe S 《Journal of structural and functional genomics》2007,8(4):167-172
Integral membrane proteins have become the focus of interest of many laboratories and structural genomics consortia, but their
study is hampered by bottlenecks in production, solubilization, purification and crystallization. In our laboratory we have
addressed the problem of high-level protein expression in the membrane of Escherichia coli by use of Mistic, a novel Bacillus subtilis protein, as a fusion partner. In this study we examine the effect of Mistic on protein expression and membrane integration
levels of members of the E. coli histidine kinase receptor family. We find that Mistic fusion invariably increases the overall yield by targeting the cargo
proteins more efficiently to the membrane and may even replace the signal sequence. Mistic fusion methods will likely be instrumental
for high-level expression of other integral membrane proteins. 相似文献
972.
Diversity of physiological cell reactivity to heat shock protein 60 in different mouse strains 总被引:1,自引:1,他引:0 下载免费PDF全文
Luna E Postol E Caldas C Mundel LR Porto G Iwai LK Ho PL Kalil J Coelho V 《Cell stress & chaperones》2007,12(2):112-122
Heat shock proteins (Hsp) are families of highly conserved molecules and immunodominant antigens in some infections and in autoimmune diseases. Some reports suggest that different regions of the Hsp60 molecule induce distinct immune responses. However, there are no reports comparing physiological T-cell reactivity to Hsp60 in mice. In this study, we have analyzed T-cell proliferation and cytokine production induced by Hsp60, under physiological conditions, in three mouse strains bearing distinct major histocompatibility complex (MHC) backgrounds. Proliferative response predominantly was found in C57BL/6 mice, mostly induced by N-terminal and intermediate Hsp60 peptides (P < 0.0001). Interferon-gamma (IFNgamma) production was broadly induced by different regions of Hsp60 in all three mouse strains, although response was focused in different peptide groups in each strain. We did not observe an exclusive Th1 or Th2 cytokine profile induced by any particular region of Hsp60. However, we identified a strain hierarchy in IL-10 production induced by Hsp60 peptides from different regions, mostly detected in C3H/HePas, and in BALB/c, but not in C57BL/6 mice. In contrast, IL-4 production only was induced by the intermediate and C-terminal region peptides in both C3H/HePas and BALB/c mice. Our data give original information on physiological cellular reactivity to Hsp60. We also have identified peptides with the capacity to induce the production of anti-inflammatory cytokines, bringing perspectives for their use in immunotherapy of chronic inflammatory diseases and allograft rejection. 相似文献
973.
Borgoño CA Gavigan JA Alves J Bowles B Harris JL Sotiropoulou G Diamandis EP 《Biological chemistry》2007,388(11):1215-1225
Human kallikrein 1-related peptidases (KLKs) form a subfamily of 15 extracellular (chymo)tryptic-like serine proteases. KLKs 4, 5, 13 and 14 display altered expression/activity in diverse pathological conditions, including cancer. However, their distinct (patho)physiological roles remain largely uncharacterized. As a step toward distinguishing their proteolytic functions, we attempt to define their primary and extended substrate specificities and identify candidate biological targets. Heterologously expressed KLKs 4, 5, 13 and 14 were screened against fluorogenic 7-amino-4-carbamoylmethylcoumarin positional scanning-synthetic combinatorial libraries with amino acid diversity at the P1-P4 positions. Our results indicate that these KLKs share a P1 preference for Arg. However, each KLK exhibited distinct P2-P4 specificities, attributable to structural variations in their surface loops. The preferred P4-P1 substrate recognition motifs based on optimal subsite occupancy were as follows: VI-QSAV-QL-R for KLK4; YFWGPV-RK-NSFAM-R for KLK5; VY-R-LFM-R for KLK13; and YW-KRSAM-HNSPA-R for KLK14. Protein database queries using these motifs yielded many extracellular targets, some of which represent plausible KLK substrates. For instance, cathelicidin, urokinase-type plasminogen activator, laminin and transmembrane protease serine 3 were retrieved as novel putative substrates for KLK4, 5, 13 and 14, respectively. Our findings may facilitate studies on the role of KLKs in (patho)physiology and can be used in the development of selective KLK inhibitors. 相似文献
974.
In the present study the green alga Scenedesmus obliquus was used to assess the effects of high salinity (high NaCl-concentration) on the structure and function of the photosynthetic apparatus and the possibility for alleviation by exogenous putrescine (Put). Chlorophyll fluorescence data revealed the range of the changes induced in the photosynthetic apparatus by different NaCl concentrations, which altogether pointed towards an increased excitation pressure. At the same time, changes in the levels of endogenous polyamine concentrations, both in cell and in isolated thylakoid preparations were also evidenced. Certain polyamine changes (Put reduction) were correlated with changes in the structure and function of the photosynthetic apparatus, such as the increase in the functional size of the antenna and the reduction in the density of active photosystem II reaction centers. Thus, exogenously added Put was used to compensate for this stress condition and to adjust the above mentioned changes, so that to confer some kind of tolerance to the photosynthetic apparatus against enhanced NaCl-salinity and permit cell growth even in NaCl concentrations that under natural conditions would be toxic. 相似文献
975.
976.
Peng XH Qian X Mao H Wang AY Chen ZG Nie S Shin DM 《International journal of nanomedicine》2008,3(3):311-321
Magnetic iron oxide (IO) nanoparticles with a long blood retention time, biodegradability and low toxicity have emerged as one of the primary nanomaterials for biomedical applications in vitro and in vivo. IO nanoparticles have a large surface area and can be engineered to provide a large number of functional groups for cross-linking to tumor-targeting ligands such as monoclonal antibodies, peptides, or small molecules for diagnostic imaging or delivery of therapeutic agents. IO nanoparticles possess unique paramagnetic properties, which generate significant susceptibility effects resulting in strong T2 and T*2 contrast, as well as T1 effects at very low concentrations for magnetic resonance imaging (MRI), which is widely used for clinical oncology imaging. We review recent advances in the development of targeted IO nanoparticles for tumor imaging and therapy. 相似文献
977.
Jane Melville Joshua Hale Georgia Mantziou Natalia B. Ananjeva Konstantin Milto Nick Clemann 《Molecular phylogenetics and evolution》2009,53(1):99-112
The Central Asian agamid lizards are ecologically and morphologically diverse, occurring across a broad range of desert environments in this biogeographically important region. It is probable that past climatic shifts have significantly influenced the diversification patterns and distributions of the agamid lizards of this region. To assess this within a phylogenetic framework we sequenced a 1200 bp region of mitochondrial DNA and a 1200 bp nuclear gene (RAG-1), incorporating both inter- and intraspecific sampling across Central Asian agamids. Our topology and divergence time estimates support an Eocene origin of the Agaminae subfamily on the Indian subcontinent, coinciding with the collision of India into Eurasia. The onset of aridification in Central Asia during the Late Oligocene, resulting from the retreat of the Paratethys Sea and the intensified uplift of the Tibetan–Himalayan complex, probably played an important role in the diversification of Phrynocephalus, one of the three genera studied. Intensification of aridity and geologic events in the Plio-Pleistocene and Quaternary glacial cycling probably had a significant influence on intraspecific diversification patterns within Phrynocephalus. 相似文献
978.
Diamanti-Kandarakis E Argyrakopoulou G Economou F Kandaraki E Koutsilieris M 《The Journal of steroid biochemistry and molecular biology》2008,109(3-5):242-246
The polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age today. Women with PCOS often demonstrate defective ovarian steroid biosynthesis and present with hyperandrogenemia. Moreover, 50-70% of PCOS women are insulin resistant and hyperinsulinemic. Insulin acts on the ovary via its own receptor and interacts with gonadotrophins, modulating steroidogenesis. The precise role of insulin and the molecular mechanisms that take place are not yet completely explicated. This review will be focused on insulin's action on the ovary and other target tissues, describing the intracellular signaling pathways implicated in steroidogenesis and their defects in women with PCOS. 相似文献
979.
Zong WX Li C Hatzivassiliou G Lindsten T Yu QC Yuan J Thompson CB 《The Journal of cell biology》2003,162(1):59-69
Bax and Bak play a redundant but essential role in apoptosis initiated by the mitochondrial release of apoptogenic factors. In addition to their presence at the mitochondrial outer membrane, Bax and Bak can also localize to the ER. Agents that initiate ER stress responses can induce conformational changes and oligomerization of Bax on the ER as well as on mitochondria. In wild-type cells, this is associated with caspase 12 cleavage that is abolished in bax-/-bak-/- cells. In bax-/-bak-/- cells, introduction of Bak mutants selectively targeted to either mitochondria or the ER can induce apoptosis. However, ER-targeted, but not mitochondria-targeted, Bak leads to progressive depletion of ER Ca2+ and induces caspase 12 cleavage. In contrast, mitochondria-targeted Bak leads to enhanced caspase 7 and PARP cleavage in comparison with the ER-targeted Bak. These findings demonstrate that in addition to their functions at mitochondria, Bax and Bak also localize to the ER and function to initiate a parallel pathway of caspase activation and apoptosis. 相似文献
980.