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81.
Hatsumi Yoshiki Matomo Nishio Yuji Ikegaya Naoya Takahashi Norio Matsuki Yasuhisa Fujibayashi Yoshiharu Yonekura Toshihiko Momiyama Ikunobu Muramatsu 《Journal of neurochemistry》2013,126(3):360-371
Muscarinic acetylcholine receptors (mAChRs) are well known to transmit extracellular cholinergic signals into the cytoplasm from their position on the cell surface. However, we show here that M1‐mAChRs are also highly expressed on intracellular membranes in neurons of the telencephalon and activate signaling cascades distinct from those of cell surface receptors, contributing uniquely to synaptic plasticity. Radioligand‐binding experiments with cell‐permeable and ‐impermeable ligands and immunohistochemical observations revealed intracellular and surface distributions of M1‐mAChRs in the hippocampus and cortex of rats, mice, and humans, in contrast to the selective occurrence on the cell surface in other tissues. All intracellular muscarinic‐binding sites were abolished in M1‐mAChR‐gene‐knockout mice. Activation of cell surface M1‐mAChRs in rat hippocampal neurons evoked phosphatidylinositol hydrolysis and network oscillations at theta rhythm, and transiently enhanced long‐term potentiation. On the other hand, activation of intracellular M1‐mAChRs phosphorylated extracellular‐regulated kinase 1/2 and gradually enhanced long‐term potentiation. Our data thus demonstrate that M1‐mAChRs function at both surface and intracellular sites in telencephalon neurons including the hippocampus, suggesting a new mode of cholinergic transmission in the central nervous system. 相似文献
82.
Jelena Baranovic Chandra S. Ramanujan Nahoko Kasai Charles R. Midgett Dean R. Madden Keiichi Torimitsu John F. Ryan 《The Journal of biological chemistry》2013,288(12):8647-8657
AMPA receptors (AMPARs) are glutamate-gated ion channels ubiquitous in the vertebrate central nervous system, where they mediate fast excitatory neurotransmission and act as molecular determinants of memory formation and learning. Together with detailed analyses of individual AMPAR domains, structural studies of full-length AMPARs by electron microscopy and x-ray crystallography have provided important insights into channel assembly and function. However, the correlation between the structure and functional states of the channel remains ambiguous particularly because these functional states can be assessed only with the receptor bound within an intact lipid bilayer. To provide a basis for investigating AMPAR structure in a membrane environment, we developed an optimized reconstitution protocol using a receptor whose structure has previously been characterized by electron microscopy. Single-channel recordings of reconstituted homomeric GluA2flop receptors recapitulate key electrophysiological parameters of the channels expressed in native cellular membranes. Atomic force microscopy studies of the reconstituted samples provide high-resolution images of membrane-embedded full-length AMPARs at densities comparable to those in postsynaptic membranes. The data demonstrate the effect of protein density on conformational flexibility and dimensions of the receptors and provide the first structural characterization of functional membrane-embedded AMPARs, thus laying the foundation for correlated structure-function analyses of the predominant mediators of excitatory synaptic signals in the brain. 相似文献
83.
Kunisuke Tanaka Toshio Sugimoto Masahiro Ogawa Zenzaburo Kasai 《Bioscience, biotechnology, and biochemistry》2013,77(7):1633-1639
Two types of proteinaceous particles were observed under the electron microscope in the starchy endosperm of rice seeds. One was spherical with lamellar structure (PB-I), while the other was stained homogeneously by osmium tetroxide and not lamellar structured (PB-II). Both types of proteinaceous particles were effectively condensed from the homogenate of developing rice endosperm by an aqueous polymer two-phase system using dextran-DEAE dextran-polyethylene glycol. Separation of both types was carried out by sucrose density gradient centrifugation. These proteinaceous particles were recovered at specific gravities of 1.27 and 1.29 for PB-I and PB-II, respectively. The protein composition of these particles and their solubility fractionation were examined. Prolamin appeared in the PB-I fraction, whereas PB-II was rich in glutelin and globulin. 相似文献
84.
A strongly acidic amino acid—N-carboxymethyl-L-serine—, not previously known in nature, has been isolated from asparagus (Asparagus officinalis) shoots. Some unique properties of this amino acid, such as a much bigger mobility to anode on high voltage paper electrophoresis (pH 3.6) than aspartic acid and characteristic changes of NMR spectra in aqueous solution with various pD, were discussed in relation to its structure. 相似文献
85.
Keishi Shimokawa Yoshinori Ueda Zenzaburo Kasai 《Bioscience, biotechnology, and biochemistry》2013,77(11):2021-2024
ABSTRACTJapanese apricot, Prunus mume Sieb. et Zucc., biosynthesizes the l-phenylalanine-derived cyanogenic glucosides prunasin and amygdalin. Prunasin has biological properties such as anti-inflammation, but plant extraction and chemical synthesis are impractical. In this study, we identified and characterized UGT85A47 from Japanese apricot. Further, UGT85A47 was utilized for prunasin microbial production. Full-length cDNA encoding UGT85A47 was isolated from Japanese apricot after 5?- and 3?-RACE. Recombinant UGT85A47 stoichiometrically catalyzed UDP-glucose consumption and synthesis of prunasin and UDP from mandelonitrile. Escherichia coli C41(DE3) cells expressing UGT85A47 produced prunasin (0.64 g/L) from racemic mandelonitrile and glucose. In addition, co-expression of genes encoding UDP-glucose biosynthetic enzymes (phosphoglucomutase and UTP-glucose 1-phosphate uridiltransferase) and polyphosphate kinase clearly improved prunasin production up to 2.3 g/L. These results showed that our whole-cell biocatalytic system is significantly more efficient than the existing prunasin production systems, such as chemical synthesis. 相似文献
86.
Kunisuke Tanaka Tetsushi Yoshida Zenzaburo Kasai 《Bioscience, biotechnology, and biochemistry》2013,77(7):1319-1325
When aleurone particles isolated from rice grains were incubated with 32P-orthophosphate or 3H-myo-inositol, both radioactivities were incorporated into an acid-stable phosphate ester. As the reaction product, myo-inositol monophosphate was recognized by ion exchange column chromatography. The phosphorylation activity was highest at the bran which corresponded to the aleurone layer. These observations suggest that the phosphorylation site of myo-inositol in the rice grain is the aleurone particles.The phosphorylation of myo-inositol was enhanced by the existence of ATP. The optimum pH and temperature for the phosphorylation were 7.9 and 30°C, respectively. 相似文献
87.
To search precursors of ethylene in banana fruits, ethylene formation from acetate-2-14C and fumarate-2,3-14C by banana slices was studied. Ethylene-14C formation from acetate-2-l4C was reduced by the addition of malonate or β-hydroxypropionate, and it was enhanced in a sealed chamber in comparison with the case in an aeration chamber. No label of fumarate-2,3-14C was incorporated into ethylene.From these facts it was suggested that acetate-2-14C was incorporated into ethylene via malonate and β-hydroxypropionate. Participation of fumarate in ethylene biosynthesis of banana fruits was ruled out. β-Hydroxypropionate was postulated as an effective precursor of ethylene formation from acetate-2-l4C. 相似文献
88.
Takanori Kasai Katsuhisa Furukawa Sadao Sakamura 《Bioscience, biotechnology, and biochemistry》2013,77(12):2489-2490
The antibacterial effects of salivary nitrate/nitrite on the growth of three Desulfovibrio species were examined. The bacteria did not grow on plates with ≥0.2 mM nitrate or ≥1.0 mM nitrite. They were also incubated in filter-sterilized saliva. D. desulfuricans was reduced on the order of >102 compared with the control solution (phosphate-buffered saline) in nine out of the 10 participants. 相似文献
89.
A methanol-utilizing phototrophic bacterium, strain M402, was isolated from surface water of an acidic hot spring. The isolated strain was identified as Rhodopseudomonas acidophila from its morphological and physiological characters. Profiles of the utilization of non-aromatic compounds as carbon sources by this strain were in good agreement with those of some strains of R. acidophila reported by Pfennig [J. Bacteriol., 99, 597 (1969)]. However, strain M402 was found to be capable of utilizing vanillic acid, vanillin, vanillyl alcohol, ferulic acid, veratric acid, syringic acid, syringal-dehyde and benzyl alcohol as carbon sources under anaerobic-light conditions. Although Pfennig did not refer to these abilities of his strains, these notable characters of strain M402 seem to be additional new characters of R. acidophila. 相似文献
90.
Takanori Kasai Minoru Sano Sadao Sakamura 《Bioscience, biotechnology, and biochemistry》2013,77(12):2449-2453
l-Ng-Methylarginine, l-Ng,Ng-dimethylarginine and ethanolamine were isolated from basic amino acids fraction of broad bean (Vicia faba L.) seed. The presence of Ng,N′g-dimethylarginine was also suggested. 相似文献