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101.
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Yoshiteru Sasaki Soichi Sano Masaki Nakahara Shigeo Murata Kohei Kometani Yuichi Aiba Shinji Sakamoto Yoshihiro Watanabe Keiji Tanaka Tomohiro Kurosaki Kazuhiro Iwai 《The EMBO journal》2013,32(18):2463-2476
The linear ubiquitin chain assembly complex (LUBAC) plays a crucial role in activating the canonical NF‐κB pathway, which is important for B‐cell development and function. Here, we describe a mouse model (B‐HOIPΔlinear) in which the linear polyubiquitination activity of LUBAC is specifically ablated in B cells. Canonical NF‐κB and ERK activation, mediated by the tumour necrosis factor (TNF) receptor superfamily receptors CD40 and TACI, was impaired in B cells from B‐HOIPΔlinear mice due to defective activation of the IKK complex; however, B‐cell receptor (BCR)‐mediated activation of the NF‐κB and ERK pathways was unaffected. B‐HOIPΔlinear mice show impaired B1‐cell development and defective antibody responses to thymus‐dependent and thymus‐independent II antigens. Taken together, these data suggest that LUBAC‐mediated linear polyubiquitination is essential for B‐cell development and activation, possibly via canonical NF‐κB and ERK activation induced by the TNF receptor superfamily, but not by the BCR. 相似文献
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Wenxiu Ye Mohammad Anowar Hossain Shintaro Munemasa Yoshimasa Nakamura Izumi C. Mori Yoshiyuki Murata 《Journal of plant physiology》2013
We recently demonstrated that endogenous abscisic acid (ABA) is involved in methyl jasmonate (MeJA)-induced stomatal closure in Arabidopsis thaliana. In this study, we investigated whether endogenous ABA is involved in MeJA-induced reactive oxygen species (ROS) and nitric oxide (NO) production and cytosolic alkalization in guard cells using an ABA-deficient Arabidopsis mutant, aba2-2, and an inhibitor of ABA biosynthesis, fluridon (FLU). The aba2-2 mutation impaired MeJA-induced ROS and NO production. FLU inhibited MeJA-induced ROS production in wild-type guard cells. Pretreatment with 0.1 μM ABA, which does not induce stomatal closure in the wild type, complemented the insensitivity to MeJA of the aba2-2 mutant. However, MeJA induced cytosolic alkalization in both wild-type and aba2-2 guard cells. These results suggest that endogenous ABA is involved in MeJA-induced ROS and NO production but not in MeJA-induced cytosolic alkalization in Arabidopsis guard cells. 相似文献
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Susumu Murata Hirokazu Matsui Seiya Chiba Tokuji Shimomura 《Bioscience, biotechnology, and biochemistry》2013,77(10):2131-2135
The substrate specificity of rice α-glucosidase II was studied. The enzyme was active especially on nigerose, phenyl-α-maltoside and maltooligosaccharides. The actions on isomaltose and phenyl-α-glucoside were weak, and on sucrose and methyl-α-glucoside, negligible. The α-glucans, such as soluble starch, amylopectin, β-limit dextrin, glycogen and amylose, were also hydrolyzed.The ratio of the maximum velocities for hydrolyses of maltose (G2), nigerose (N), kojibiose (K), isomaltose (I), phenyl-α-maltoside (?M) and soluble starch (SS) was estimated to be 100: 94.4: 14.2: 7.1: 89.5: 103.1 in this order, and that for hydrolyses of malto-triose (G3), -tetraose (G4), -pentaose (G5), -hexaose (G6), -heptaose (G7), -octaose (G8), and amyloses ( and ), 113: 113: 113: 106: 113: 100: 106: 106. The Km values for N, K, I, ?M and SS were 2.4 mm, 0.58 mm, 20 mm, 1.6 mm and 5.0 mg/ml, respectively; those for G2, G3, G4, G5, G6, G7, G8, and , 2.4 mm, 2.2 mm, 2.1 mm, 1.5 mm, 1.0 mm, 1.1 mm, 0.95 mm, 1.5 mm and 1.1 mm.Rice α-glucosidase II is considered an enzyme with a preferential activity on maltooligosaccharides. 相似文献
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Takao Murata 《Bioscience, biotechnology, and biochemistry》2013,77(10):1995-2002
ADP-glucose phosphorylase [adenosine diphosphate glucose: orthophosphate adenyl- yltransferase; Dankert et ah, Biochim. Biophys. Acta, 81, 78 (1964)] was found to be widely distributed in plant tissues. The enzyme was purified 570-fold in a 24% yield from cell- free extract of growing tubers of potato (Solanum tuberosum L.). The following reaction catalyzed by the purified enzyme was found to proceed stoichiometrically. ADP-glucose +P1→ADP+glucose-1-PMaximal activity was observed at pH 8. The enzyme was the most stable at pH 7, showing 50% loss of its original activity after 50 min heating at 57°C. The following kinetic parameters were obtained: activation energy, 11.1 kcal/mole; Km (P1), 2.5 mm; Km (ADP-glucose), 0.05 mm. The enzyme did not act on GDP-mannose, GDP-glucose and UDP-glucose. Neither activator nor inhibitor was found among various phosphorylated metabolites tested. The enzyme was inhibited by metal-binding reagents, EDTA and o-phenanthroline. None of the metal ions tested was found to recover the activity of chelator-treated enzyme. 相似文献