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161.
The conditions that favor the in vitro synthesis of cellulose from tobacco BY-2 cell extracts were determined. The procedure leading to the highest yield of cellulose consisted of incubating digitonin extracts of membranes from 11-day-old tobacco BY-2 cells in the presence of 1 mM UDP-glucose, 8 mM Ca2+ and 8 mM Mg2+. Under these conditions, up to nearly 40% of the polysaccharides synthesized in vitro corresponded to cellulose, the other polymer synthesized being callose. Transmission electron microscopy an... 相似文献
162.
Nucleotide sequence of a yeast tRNAArg3A gene and its transcription in a homologous in vitro system 总被引:4,自引:0,他引:4
Neutrophil homogenates contained a high affinity guanosine triphosphatase (GTPase) that was stimulatable (+27%) by the addition of 100 nM N-formyl chemotactic peptide (CHO-pep), but not by 1 microgram X ml-1 phorbolmyristate acetate (PMA). Kinetic analysis of the stimulation demonstrated an apparent lagtime of 14.3 +/- 6.9 s between the addition of CHO-pep and the optimal GTPase stimulation. The GTPase activity (but not CHO-pep-stimulated GTPase activity) was preserved in a highly purified plasma membrane fraction of the homogenate. From these observations we suggest that both a high affinity guanine nucleotide binding protein and GTPase are closely associated with the plasma membrane CHO-pep receptor. The possibility that GTPase activity may influence guanine nucleotide regulation of adenylate cyclase during CHO-pep stimulation of neutrophils is discussed. 相似文献
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P Valenzuela P Bull J Zaldivar A Venegas J Martial 《Biochemical and biophysical research communications》1978,81(2):662-666
Ovine mammary gland mRNAs were translated in a wheat-germ cell-free system in the presence of radioactive amino acids. Automated Edman degradation performed on α-lactalbumin isolated by immunoprecipitation from the mixture of radiolabelled lactoproteins showed the occurrence of an hydrophobic 19 residues long amino terminal extension. The pre-protein represents the primary translation product since the amino terminal methionyl residue was found to be donated by initiator . Comparison of the signals of ovine α-lactalbumin and hen's egg white lysozyme, two homologous proteins which are thought to be derived from a common ancestor, suggests that the signal region has evolved at least as rapidly as the remaining part of the polypeptide chain. 相似文献
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Morphologic, cytochemical and immunocytochemical studies of pericardial fluid from a 30-year-old man presenting with cardiac tamponade are described. Based on the results of the immunocytochemical studies and the histologic examination of excised pericardium, a diagnosis of malignant thymoma was made. This is the first documented case in which malignant cells were found in the pericardial effusion in a patient with invasive thymoma. The significance of using a multidisciplinary approach to the study of body fluids is discussed. 相似文献
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