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991.
Ribonuclease A (RNase A) dimers have been recently found to be endowed with some of the special, i.e., non-catalytic biological activities of RNases, such as antitumor and aspermatogenic activities. These activities have been so far attributed to RNases which can escape the neutralizing action of the cytosolic RNase inhibitor (cRI). However, when the interactions of the two cytotoxic RNase A dimers with cRI were investigated in a quantitative fashion and at the molecular level, the dimers were found to bind cRI with high affinity and to form tight complexes. 相似文献
992.
Water channel activities of Mimosa pudica plasma membrane intrinsic proteins are regulated by direct interaction and phosphorylation 总被引:4,自引:0,他引:4
Temmei Y Uchida S Hoshino D Kanzawa N Kuwahara M Sasaki S Tsuchiya T 《FEBS letters》2005,579(20):4417-4422
cDNAs encoding aquaporins PIP1;1, PIP2;1, and TIP1;1 were isolated from Mimosa pudica (Mp) cDNA library. MpPIP1;1 exhibited no water channel activity; however, it facilitated the water channel activity of MpPIP2;1 in a phosphorylation-dependent manner. Mutagenesis analysis revealed that Ser-131 of MpPIP1;1 was phosphorylated by PKA and that cooperative regulation of the water channel activity of MpPIP2;1 was regulated by phosphorylation of Ser-131 of MpPIP1;1. Immunoprecipitation analysis revealed that MpPIP1;1 binds directly to MpPIP2;1 in a phosphorylation-independent manner, suggesting that phosphorylation of Ser-131 of MpPIP1;1 is involved in regulation of the structure of the channel complex with MpMIP2;1 and thereby affects water channel activity. 相似文献
993.
Terziyska N Lutz T Kozany C Mokranjac D Mesecke N Neupert W Herrmann JM Hell K 《FEBS letters》2005,579(1):179-184
Many proteins located in the intermembrane space (IMS) of mitochondria are characterized by a low molecular mass, contain highly conserved cysteine residues and coordinate metal ions. Studies on one of these proteins, Tim13, revealed that net translocation across the outer membrane is driven by metal-dependent folding in the IMS . We have identified an essential component, Mia40/Tim40/Ykl195w, with a highly conserved domain in the IMS that is able to bind zinc and copper ions. In cells lacking Mia40, the endogenous levels of Tim13 and other metal-binding IMS proteins are strongly reduced due to the impaired import of these proteins. Furthermore, Mia40 directly interacts with newly imported Tim13 protein. We conclude that Mia40 is the first essential component of a specific translocation pathway of metal-binding IMS proteins. 相似文献
994.
Ogawa Y Morikawa N Ohkubo-Suzuki A Miyoshi S Arakawa H Kita Y Nishimura S 《Biotechnology and bioengineering》2005,92(7):865-870
We discovered an epoch-making gene transfer method utilizing discharge plasma. Although an electroporation method is commonly used in present gene transfer experiments, it cannot transfer genes into primary cells sufficiently. The atmospheric pressure discharge plasma employed in this study was originally used for surface treatment of non-biological materials. We hypothesized that it could provide a suitable effect on the surface of target cells and applied it to gene transfer into various types of cells. The plasma technology succeeded in the efficient transfer of green fluorescence protein (GFP) plasmid into post-mitotic neuronal cells obtained from cerebral cortices of rats, into which an electroporation with conventional equipment cannot transfer genes sufficiently, as the cells were attached. After the transfection of rat pheochromocytoma PC12 cells with the GFP gene by plasma treatment, the cells retained their function, that is, nerve growth factor-induced differentiation. Furthermore, gene transfer with the plasma technology was also applicable to other types of cell lines such as HeLa cells and Chinese hamster lung (CHL) cells as adherent cell lines, and Jurkat cells as a suspended cell line, and another type of primary cell, human umbilical vein endothelial cells (HUVEC). In conclusion, the plasma method is an epoch-making gene transfer technology which efficiently transfers genes into primary cells into which electroporation cannot transfer genes. Moreover, the method is able to universally transfer genes into various types of cells as the function of the cells was maintained. 相似文献
995.
Udby L Lundwall A Johnsen AH Fernlund P Valtonen-André C Blom AM Lilja H Borregaard N Kjeldsen L Bjartell A 《Biochemical and biophysical research communications》2005,333(2):555-561
beta-Microseminoprotein (MSP) and cysteine-rich secretory protein 3 (CRISP-3) are abundant constituents of human seminal plasma. Immunoprecipitation and gel filtration of seminal plasma proteins combined with examination of the proteins in their pure form showed that MSP and CRISP-3 form stable, non-covalent complexes. CRISP-3 binds MSP with very high affinity, as evidenced by surface plasmon resonance. Due to far higher abundance of MSP in prostatic fluid, it manifests large overcapacity for CRISP-3 binding. Structural similarity with an MSP-binding protein from blood plasma suggests that CRISP-3 binds MSP through its aminoterminal SCP-domain. 相似文献
996.
Vikinge TP Hansson KM Sandström P Liedberg B Lindahl TL Lundström I Tengvall P Höök F 《Biosensors & bioelectronics》2000,15(11-12):605-613
The coagulation of blood plasma and whole blood was studied with a surface plasmon resonance (SPR) based device and a quartz crystal microbalance instrument with energy dissipation detection (QCM-D). The SPR and QCM-D response signals were similar in shape but differing in time scales, reflecting differences in detection mechanisms. The QCM-D response time was longer than SPR, as a physical coupling of the sample to the substrate is required for molecules to be detected by the QCM-method. Change of sample properties within the evanescent field is sufficient for detection with SPR. Both the SPR signals and the QCM-D frequency and dissipation shifts showed dependency on concentrations of coagulation activator and sensitivity to heparin additions. The ratio of dissipation to frequency shifts, commonly considered to reflect viscoelastic properties of the sample, varied with the concentration of activator in blood plasma but not in whole blood. Additions of heparin to the thromboplastin activated whole blood sample, however, made the ratio variation reoccur. Implications of these observations for the understanding of the blood coagulation processes as well as the potential of the two methods in the clinic and in research are discussed. 相似文献
997.
Ivanchenko M Vejlupkova Z Quatrano RS Fowler JE 《The Plant journal : for cell and molecular biology》2000,24(1):79-90
Signals in the carboxy-terminal hypervariable region (HVR) of Rho and Ras GTPases target these proteins to specific membrane compartments, where they function in signal transduction. ROP6 and ROP7 are closely related maize Rops (a plant-specific Rho subgroup) that share HVR sequences divergent from other Rho HVRs. Both ROPs terminate in CAA, instead of the consensus C-terminal CaaX motif required for membrane association of all characterized Ras and Rho GTPases. The ROP6/7 HVR contains two additional cysteines, potential sites for post-translational modification that leads to membrane association; one is in an internal CaaX motif, which would be at the C-terminus if the final intron in both genes were not removed. Transient expression of a GFP-ROP7 fusion revealed its near-total association with the plasma membrane (PM). Furthermore, the ROP7 HVR is sufficient to target GFP to the PM. Surprisingly, the cysteine in the terminal CAA is not required for PM targeting of GFP-ROP7. In contrast, an internal HVR cysteine is essential for proper targeting of the fusion, and the cysteine in the internal CaaX is required for complete membrane association. Interestingly, this CaaX motif can also direct PM association when placed at the fusion C-terminus by addition of an internal stop codon. Fractionation experiments confirm that maize ROPs associate with membranes in maize seedlings. Our analysis suggests that the ROP7 HVR directs PM localization by a mechanism independent of a C-terminal CaaX motif; this mechanism may have evolved through addition of 3' intron/exon sequences to a rop progenitor. 相似文献
998.
Changes in lipid peroxidation, the redox system and ATPase activities in plasma membranes of rice seedling roots caused by lanthanum chloride 总被引:10,自引:0,他引:10
Hai-Lei Zheng Zhong-Qiu Zhao Chun-Guang Zhang Jin-Zhao Feng Zen-Lian Ke Ming-Jia Su 《Biometals》2000,13(2):157-163
Highly purified plasma membranes were isolated by aqueous two-phase partitioning from rice (Oryza sativa) seedling roots. The effects of lanthanum chloride (LaCl3) on the activities of lipid peroxidation, the redox system and H+-ATPase, Ca2+-ATPase of plasma membranes were studied. The lipid peroxidation of plasma membranes could be depressed by certain low concentrations of LaCl3 and enhanced by high concentrations of LaCl3, while the lipid peroxidation was also dependent on the plasma membrane protein and incubation time. The relative activity of O2 uptake of plasma membranes was inhibited by all tested LaCl3 concentrations. In contrast, the reduction rate of Fe(CN)6
3– by plasma membranes was stimulated below 40 M of LaCl3, but was reduced above 60 M of LaCl3. The relative activities of both H+-ATPase and Ca2+-ATPase increased constantly from control to LaCl3 of concentration 60 M where the activities of both enzymes were the maximum, but decreased remarkably at 80 M LaCl3 concentrations various LaCl3 were added to culture solutions. In the other measurement case in which various LaCl3 concentrations were added directly to reaction medium and the plasma membrane vesicles only came from the control cultured rice seedling roots, the response of H+-ATPase activity to La3+ was similar to the response in culture solution. However, the La3+ concentration was only 20 M when the activity of H+-ATPase was the maximum. In contrast to the case of LaCl3 addition to culture solution, Ca2+-ATPase activity was inhibited by all concentrations of La3+ which were added directly to the reaction medium. The above results revealed that REEs inhibited electron transfer from NADH to oxygen in plant plasma membranes, depressed the production of active oxygen radicals, and reduced the formation of lipid peroxides through plasma membrane lipid peroxidation. REEs ions also enhanced the H+ extrusion by both standard redox system and H+-ATPase in plasma membranes at certain concentrations. A possible role for the plant cell wall in REEs effects on plasma membranes was also suggested. 相似文献
999.
Intestinal cholesterol absorption is substantially reduced in mice deficient in both ABCA1 and ACAT2 总被引:2,自引:0,他引:2
Temel RE Lee RG Kelley KL Davis MA Shah R Sawyer JK Wilson MD Rudel LL 《Journal of lipid research》2005,46(11):2423-2431
The process of cholesterol absorption has yet to be completely defined at the molecular level. Because of its ability to esterify cholesterol for packaging into nascent chylomicrons, ACAT2 plays an important role in cholesterol absorption. However, it has been found that cholesterol absorption is not completely inhibited in ACAT2-deficient (ACAT2 KO) mice. Because ABCA1 mRNA expression was increased 3-fold in the small intestine of ACAT2 KO mice, we hypothesized that ABCA1-dependent cholesterol efflux sustains cholesterol absorption in the absence of ACAT2. To test this hypothesis, cholesterol absorption was measured in mice deficient in both ABCA1 and ACAT2 (DKO). Compared with wild-type, ABCA1 KO, or ACAT2 KO mice, DKO mice displayed the lowest level of cholesterol absorption. The concentrations of hepatic free and esterified cholesterol and gallbladder bile cholesterol were significantly reduced in DKO compared with wild-type and ABCA1 KO mice, although these measures of hepatic cholesterol metabolism were very similar in DKO and ACAT2 KO mice. We conclude that ABCA1, especially in the absence of ACAT2, can have a significant effect on cholesterol absorption, although ACAT2 has a more substantial role in this process than ABCA1. 相似文献
1000.
Kłapcińska B Poprzecki S Danch A Sobczak A Kempa K 《Biological trace element research》2005,108(1-3):1-15
The selenium status and the relationship of whole-blood selenium and plasma homocysteine are reported for healthy human subjects
living in Upper Silesia. A total of 1063 individuals (627 male and 436 female) examined for whole-blood selenium were subdivided
into six groups according to age; the youngest included adolescents (n=143) aged 10–15 yr, and the oldest were centenarians (n=132). The mean Se content was relatively low (62.5±18.4 μg/L), and it tended to be higher in men (65.9±17.2 μg/L) than in
women (57.5±18.9 μg/L). Selenium levels appeared to be age dependent, as the highest values were observed in young and middle-age
adults (21–40 yr), whereas they were significantly lower in adolescents and in the elderly. In more than 40% of apparently
healthy adults (aged 21–69 yr), the Se concentration was within the range 60–80 μg/L (i.e., below the lower limit of the nutritional
adequacy range [80 μg/L]). A significant inverse correlation between whole-blood selenium and plasma total homocysteine was
detected in a smaller population sample of middle-aged and elderly persons (n=204). 相似文献