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11.
Plasmodium falciparum protein associated with the invasion junction contains a conserved oxidoreductase domain 总被引:2,自引:0,他引:2
Diana E. Hudson-Taylor Stephen A. Dolan Francis W. Klotz Hisashi Fujioka Masamichi Aikawa Eugene V. Koonin Louis H. Miller 《Molecular microbiology》1995,15(3):463-471
The merozoite cap protein-1 (MCP-1) of Plasmodium falciparum follows the distribution of the moving Junction during invasion of erythrocytes. We have cloned the gene encoding this protein from a cDNA library using a monoclonal antibody. The protein lacks a signal sequence and has no predicted trans-membrane domains; none of the antisera reacts with the surfaces of intact merozoites, indicating that the cap distribution is submembranous. MCP-1 is divided into three domains. The N-terminal domain includes a 52-amino-acid region that is highly conserved in a large family of bacterial and eukaryotic proteins. Based on the known functions of two proteins of this family and the pattern of amino acid conservation, it is predicted that this domain may possess oxido-reductase activity, since the active cysteine residue of this domain is invariant in all proteins of the family. The other two domains of MCP-1 are not found in any other members of this protein family and may reflect the specific function of MCP-1 in invasion. The middle domain is negatively charged and enriched in glutamate; the C-terminal domain is positively charged and enriched in lysine. By virtue of its positive charge, the C-terminal domain resembles domains in some cytoskeleton-associated proteins and may mediate the interaction of MCP-1 with cytoskeleton in Plasmodium. 相似文献
12.
13.
Masamichi Takahashi 《Journal of plant research》1984,97(2):233-245
Pollen grains ofParis, Medeola, andScoliopus have been examined with light, scanning electron, and transmission electron microscopies.P. quadrifolia L.,P. verticillata Bieb.,P. delavayi Franch. andP. polyphylla Smith have monosulcate pollen characterized by psilate, foveolate or reticulate exine sculpture. In contrast to the former
species,P. japonica (Fr. et Sav.) Franch. andP. tetraphylla A. Gray have monosulcate pollen with gemmate (rarely rugulate) exine.Medeola has monosulcate pollen with reticulate exine that is distinct from that ofParis. Scoliopus has monosulcate pollen characterized by a peculiar reticulate exine pattern. The palynological evidence suggests thatParis andTrillium are closely related to each other, andMedeola andScoliopus should be separated fromParis andTrillium. 相似文献
14.
15.
Daniel Vinella Aline Jaff Richard D'ari Masamichi Kohiyama Patrick Hughes 《Journal of bacteriology》1992,174(7):2388-2390
Escherichia coli dam mutants, lacking the GATC DNA methylase, do not produce anucleate cells at high frequencies, suggesting that hemimethylation of the chromosome origin of replication, oriC, is not essential for correct chromosome partitioning. 相似文献
16.
Purification of recombinant protein A by aqueous two-phase extraction integrated with affinity precipitation 总被引:3,自引:0,他引:3
Aqueous two-phase extraction incorporated affinity precipitation was examined as a technique for protein purification. An enteric coating polymer, Eudragit S100, was employed as a ligand carrier. Eudragit was specifically partitioned to the top phase in the aqueous two-phase systems. For application of this method to purification of recombinant protein A using human IgG coupled to Eudragit in an aqueous two-phase system, 80% of protein A added was recovered with 81% purity. The purity was enhanced 26-fold by thid method. The IgG-Eudragit could be used repeatedly for the purification process. This seperation method should be applicable to industrial-scale purification as a new purification procedure combining the advantages and compensating for the disadvantages of the aqueous two-phase method and affinity precipitation method. (c) 1992 John Wiley & Sons, Inc. 相似文献
17.
Changes in Electrophoretic Patterns of Oocyte Proteins during Oocyte Maturation in Oryzias latipes 总被引:2,自引:2,他引:0
Takashi Iwamatsu Susumu Y. Takahashi Masamichi Oh-ishi Takashi Yokochi Hiroko Maeda 《Development, growth & differentiation》1992,34(2):173-179
Changes in the two-dimensional SDS-electrophoretic patterns of extracts of maturing denuded oocytes of the medaka ( Oryzias latipes ) were surveyed. In oocytes without follicular constituents several proteins became detectable in the area between the acidic and slightly basic proteins on the two-dimensional electrophoretograms, while a few of the protein spots disappeared during the process of oocyte maturation. The former proteins were detected also in oocytes that were induced to mature in vivo without breakdown of the germinal vesicle. Several proteins newly observed in extracts of post-vitellogenic oocytes during maturation after breakdown of the germinal vesicle were also identified by two-dimensional electrophoresis. Of several proteins that exhibited noticeable changes in maturing oocytes, only one spot incorporated 14 C-labeled amino acid during maturation, suggesting that post-translational modification of many proteins occurred during oocyte maturation. 相似文献
18.
Hydrogen exchange kinetics of nucleic acids: Double and triple helices with Hoogsteen-type basepairs
Yuzuru Hayashi Mamoru Nakanishi Masamichi Tsuboi Toshikazu Fukui Morio Ikehara Ichiro Tazawa Yasuo Inoue 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,698(1):93-99
The kinetics of hydrogen-tritium exchange reaction have been followed by a Sephadex technique of a double-helical poly(ribo-2-methylthio-adenylic acid)·poly(ribouridylic acid) complex with the Hoogsteen-type basepair. Only one hydrogen in every 2-methylthio-adenine·uracil basepair has been found to exchange at a measurably slow rate, 0.023 s?1 (at 0°C), which is, however, much greater than that for a double-helix with the Watson-Crick type A·U pair. The kinetics of hydrogen-tritium exchange were also examined by triple-helical poly(rU)·poly(rA)·poly(rU) which involves both the Watson-Crick and Hoogsteen basepairings. Here, three hydrogens in every U·A·U base triplet have been found to exchange at a relatively slow rate, 0.0116 s?1 (at 0°C). The kinetics of hydrogen-deuterium exchange reactions of these polynucleotide helices have also been followed by a stopped-flow ultraviolet absorption spectrophotometry at various temperatures. On the basis of these experimental results, the mechanism of the hydrogen exchange reactions in these helical polynucleotides was discussed. In the triple helix, the rate-determining process of the slow exchange of the three (one uracil-imide and two adenine-amino) hydrogens is considered to be the opening of the Watson-Crick part of the U·A·U triplet. This opening is considered to take place only after the opening of the Hoogsteen part of the triplet. 相似文献
19.
Thomas M. Seed Darlene Brindley Masamichi Aikawa John Rabbege 《Experimental parasitology》1976,40(3):380-390
The osmotic properties of intraerythrocytic and ultrasonically liberated malaria parasites (Plasmodium berghei) were analyzed and compared with those of mouse host erythrocytes utilizing a multiple tube fragility test. Cells were incubated in phosphate buffered saline solutions of varying osmolalities ranging from 20–4000 mOsm. Changes in cell ultrastructure and parasite infectivity were used as indicators of osmotic damage. Intraerythrocytic and host cell-free plasmodia showed similar patterns of cell alteration and changes in infectivity following osmotic stress. The various developmental forms within each of the preparations responded somewhat differently to hypo-osmotic stress, however. The majority of merozoites seemed to be more sensitive than many trophozoites, schizonts, and segmenters. Small trophozoites were, on the average, more resistant than other developmental forms. Incubation of parasite populations in hypotonic salt solutions with osmolalities slightly greater than the infectivity threshold of 100 mOsm lysed the majority of the merozoites, whereas many small trophozoites were still intact. While normal erythrocytes were more resistant to hypo-osmotic stress than were either intracellular or free parasites, the majority of parasitized erythrocytes was less resistant than normal erythrocytes. The predominant alteration induced by hyperosmotic stress appears in the parasite's nuclear region with myelination of the nuclear membranes and chromatin clumping. The infectivity threshold in the hypertonic range was found to be approximately 2500 mOsm. Results indicate that these obligate intracellular parasites have a wide range of osmotic sensitivities and that they are capable of existing for short periods in various osmotic environments ranging from 100–2500 mOsm without complete loss of infectivity. This suggests that these parasites have osmotic regulatory capabilities at least comparable to those of host cells. 相似文献
20.
Masamichi Takagi 《Biochemical and biophysical research communications》1975,63(4):839-844
A cytoplasmic post-mitochondrial extract (Sephadex-PM) from rat liver was active in incorporating [14C]methyl labeled choline into acid insoluble membrane material. The result of analysis of labeled phospholipid showed that most of the radioactivity was in lecithin. When Sephadex-PM was pre-incubated with hexobarbital, the choline incorporating activity was stimulated. Phenobarbital, but not 3-methylcholanthrene, also stimulated the incorporation. And the degree of the stimulation was dependent on the concentration of the drugs. 相似文献