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PM28A is a major intrinsic protein of the spinach leaf plasma membrane and the major phosphoprotein. Phosphorylation of PM28A is dependent in vivo on the apoplastic water potential and in vitro on submicromolar concentrations of Ca2+. Here, we demonstrate that PM28A is an aquaporin and that its water channel activity is regulated by phosphorylation. Wild-type and mutant forms of PM28A, in which putative phosphorylation sites had been knocked out, were expressed in Xenopus oocytes, and the resulting increase in osmotic water permeability was measured in the presence or absence of an inhibitor of protein kinases (K252a) or of an inhibitor of protein phosphatases (okadaic acid). The results indicate that the water channel activity of PM28A is regulated by phosphorylation of two serine residues, Ser-115 in the first cytoplasmic loop and Ser-274 in the C-terminal region. Labeling of spinach leaves with 32P-orthophosphate and subsequent sequencing of PM28A-derived peptides demonstrated that Ser-274 is phosphorylated in vivo, whereas phosphorylation of Ser-115, a residue conserved among all plant plasma membrane aquaporins, could not be demonstrated. This identifies Ser-274 of PM28A as the amino acid residue being phosphorylated in vivo in response to increasing apoplastic water potential and dephosphorylated in response to decreasing water potential. Taken together, our results suggest an active role for PM28A in maintaining cellular water balance.  相似文献   
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The authors of the present article were the first to work out theoretical foundations and methods of physiological diagnosis of neurocirculatory dystonia. Criteria of tension of myocardial functional structures and central regulatory mechanisms have been identified both in healthy subjects and cardiological patients. It has been ascertained that degree and systematic character of tension cause the physiological risk factors for cardio-pathology to develop, 6 types were identified of loading adaptation of the heart caused by extent of its tension, in individuals with neurocirculatory dystonia. Each of the types disclosed is characterized by a dynamics of the functional volumes proportions as well as by peculiarities of the adaptation mechanisms. Physiological diagnosis of functioning of the heart is one of major methods of the primary prophylaxis of neurocirculatory dystonias as well as prevention of aggravation of their course.  相似文献   
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A new system for the expression of a catalytic light chain antibody to the vasoactive intestinal peptide is described. The system made possible the isolation the large amounts of a homogeneous protein without any additional peptide domains. The preparation obtained can be used in further experiments on light chain crystallization and in X-ray-structural analysis of its catalytic center.  相似文献   
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Necrotizing fasciitis is a rare soft tissue infection with a high rate of mortality. Decreased capacity of the immune response is the overall disposing factor. Necrotizing fasciitis can develop very rapidly, and a rapid diagnosis and aggressive surgery provides the best prognosis.  相似文献   
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Conclusions It was shown to be possible to obtain fused calcium oxide by plasma fusion. The fused calcium oxide is characterized by a dense structure and an increased resistance in moist atmospheres.Translated from Ogneupory, No. 5, pp. 56–58, May, 1971.  相似文献   
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