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41.
Ettrich R Brandt W Kopecký V Baumruk V Hofbauerová K Pavlícek Z 《Biological chemistry》2002,383(10):1667-1676
With respect to the mechanism of chaperone-like activity, we examined the behavior of haptoglobin under heat shock conditions. Secondary structure changes during heat treatment were followed by circular dichroism, Raman and infrared spectroscopy. A model of the haptoglobin tetramer, based on its sequence homology with serine proteases and the CCP modules, has been proposed. Sequence regions responsible for the chaperone-like activity were not fully identical with the region that takes part in formation of the hemoglobin-haptoglobin complex. We can postulate the presence of at least two different chaperone-binding sites on each haptoglobin heavy chain. 相似文献
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Kubala M Hofbauerová K Ettrich R Kopecký V Krumscheid R Plásek J Teisinger J Schoner W Amler E 《Biochemical and biophysical research communications》2002,297(1):154-159
The ATP-binding site of Na(+)/K(+)-ATPase is localized on the large cytoplasmic loop of the alpha-subunit between transmembrane helices H(4) and H(5). Site-directed mutagenesis was performed to identify residues involved in ATP binding. On the basis of our recently developed model of this loop, Ser(445), Glu(446), and Phe(475) were proposed to be close to the binding pocket. Replacement of Phe(475) with Trp and Glu(446) with Gln profoundly reduced the binding of ATP, whereas the substitution of Ser(445) with Ala did not affect ATP binding. Fluorescence measurements of the fluorescent analog TNP-ATP, however, indicated that Ser(445) is close to the binding site, although it does not participate in binding. 相似文献
43.
Do phytotropins inhibit auxin efflux by impairing vesicle traffic? 总被引:12,自引:0,他引:12
Petrásek J Cerná A Schwarzerová K Elckner M Morris DA Zazímalová E 《Plant physiology》2003,131(1):254-263
Phytotropins such as 1-N-naphthylphthalamic acid (NPA) strongly inhibit auxin efflux, but the mechanism of this inhibition remains unknown. Auxin efflux is also strongly decreased by the vesicle trafficking inhibitor brefeldin A (BFA). Using suspension-cultured interphase cells of the BY-2 tobacco (Nicotiana tabacum L. cv Bright-Yellow 2) cell line, we compared the effects of NPA and BFA on auxin accumulation and on the arrangement of the cytoskeleton and endoplasmic reticulum (ER). The inhibition of auxin efflux (stimulation of net accumulation) by both NPA and BFA occurred rapidly with no measurable lag. NPA had no observable effect on the arrangement of microtubules, actin filaments, or ER. Thus, its inhibitory effect on auxin efflux was not mediated by perturbation of the cytoskeletal system and ER. BFA, however, caused substantial alterations to the arrangement of actin filaments and ER, including a characteristic accumulation of actin in the perinuclear cytoplasm. Even at saturating concentrations, NPA inhibited net auxin efflux far more effectively than did BFA. Therefore, a proportion of the NPA-sensitive auxin efflux carriers may be protected from the action of BFA. Maximum inhibition of auxin efflux occurred at concentrations of NPA substantially below those previously reported to be necessary to perturb vesicle trafficking. We found no evidence to support recent suggestions that the action of auxin transport inhibitors is mediated by a general inhibition of vesicle-mediated protein traffic to the plasma membrane. 相似文献
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Harvati K 《Journal of human evolution》2003,44(1):107-132
The Neanderthal taxonomic position is a matter of wide disagreement among paleoanthropologists. Some workers consider this fossil human group to represent a different species, Homo neanderthalensis, while others see it as a subspecies of Homo sapiens. This study developed two models of morphological variation to be applied to a comparison between Neanderthals and modern humans: modern human populations provided a measure of intra-specific variation, while the species and subspecies of Pan provided measures of both intra- and inter-specific morphological differences. Although such an approach has been advocated strongly, it has not been systematically undertaken until recently. The techniques of geometric morphometrics were used to collect data in the form of three-dimensional coordinates of craniofacial landmarks. The data were processed using generalized procrustes analysis, and analyzed by an array of multivariate statistical methods, including principal components analysis, canonical variates analysis and Mahalanobis D(2). The morphological distances between Neanderthals and modern humans, and between Neanderthals and Late Paleolithic/early anatomically modern specimens, are consistently greater than the distances among recent human populations, and greater than the distances between the two chimpanzee species. Furthermore, no strong morphological similarities were found between Neanderthals and Late Paleolithic Europeans. This study does not find evidence for Neanderthal contribution to the evolution of modern Europeans. Results are consistent with the recognition of Neanderthals as a distinct species. 相似文献
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Kremastinou J Tzanakaki G Levidiotou S Markou F Themeli E Voyiatzi A Psoma E Theodoridou M Blackwell CC 《FEMS immunology and medical microbiology》2003,39(1):23-29
In response to an increase in the number of cases of invasive meningococcal disease (IMD) in northern regions of Greece, a survey was carried out to determine if there was an increase in carriage of Neisseria meningitidis, particularly in areas where there have been increases in immigrant populations from neighbouring countries. The second objective was to determine if there was an increase in the serogroup C:2a:P1.5,2 a phenotype associated with recent outbreaks or changes in antibiotic sensitivities. As carriage of Neisseria lactamica is associated with development of natural immunity to IMD, the third objective was to determine the carriage rate of N. lactamica in this population. Among 3167 individuals tested, meningococci were isolated from 334 (10.5%). Compared with our previous studies, the proportion of meningococcal carriers was significantly increased among children in secondary education (11.3%) (chi2=9.67, P<0.005) and military recruits (37.4%) (chi2=21.11, P<0.000). Only 5/334 (1.5%) isolates expressed the phenotype associated with the increase in IMD in Greece. N. lactamica was isolated from 146/3167 (4.6%) participants. It was isolated from 71/987 (7.2%) children attending primary or nursery schools; however, the highest proportion of carriers (11.3%) was found in the boarding school for young Albanian men. In the 21-59-year age range, the majority of N. lactamica isolates (22/25, 88%) were from women, probably due to closer or more prolonged contact with children in the primary school age range. Smoking was significantly associated with isolation of meningococci from men but not from women. Penicillin-insensitive strains (25/334, 7.5%) were identified in all four regions examined; the majority (14/25, 56%) were obtained from military personnel. We conclude that there was a higher proportion of carriers in the population of northern Greece; however, the increase in carriage rate was not associated with the influx of immigrants from neighbouring countries, and there was not a higher incidence of the C:2a:P1.5,2 strain responsible for increased disease activity in Greece in either the immigrant or local populations. 相似文献
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Katerina A. Christopoulos Susan Olender Andrea M. Lopez Helen-Maria Lekas Jessica Jaiswal Will Mellman Elvin Geng Kimberly A. Koester 《PLoS medicine》2015,12(8)