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151.
Ogura T Osawa H Tang Y Onuma H Ochi M Nishimiya T Kubota N Terauchi Y Kadowaki T Makino H 《FEBS letters》2003,542(1-3):65-68
Phosphodiesterase 3B (PDE3B) gene expression is generally reduced in large adipocytes of obese, insulin-resistant mice. This reduced gene expression is restored by peroxisome proliferator-activated receptor (PPAR) gamma ligands accompanied by a reduced fat cell size. To determine whether PDE3B gene expression is regulated by PPAR gamma itself, we analyzed lean PPAR gamma (+/-) mice with adipocyte size comparable to control PPAR gamma (+/+) mice. In adipocytes of PPAR gamma (+/-) mice, PDE3B mRNA and protein were both reduced to 63% of wild-type levels. Basal PDE activity tended to be decreased to 70% of wild-type levels, and, similarly, insulin-induced PDE activity was significantly decreased to 70%. Thus, PPAR gamma is required for PDE3B gene expression independent of adipocyte size. 相似文献
152.
Wada K Tada T Nakamura Y Ishikawa T Yabuta Y Yoshimura K Shigeoka S Nishimura K 《Journal of biochemistry》2003,134(2):239-244
Ascorbate peroxidase (APX) is a heme-containing protein that plays a central role in scavenging H(2)O(2) in higher plants. The structure of stromal APX (sAPX) was determined at 1.6 A to an R-factor of 19.1% and an R-free-factor of 22.3%. The electrostatic potential of the gamma-channel that connects the molecular surface of sAPX to the gamma-edge of heme was more positive than that of cytosolic APX (cAPX) from pea, so sAPX might bind more easily with ascorbate than cAPX. The overall structure of sAPX was similar to those of cAPX from pea and cytochrome c peroxidase (CCP) from yeast, with a substantial difference in a loop structure located in the vicinity of the heme. The side chain of Arg169 in sAPX corresponding to His169 in cAPX and His181 in CCP extended in the opposite direction from the heme, forming two hydrogen bonds with carbonyl groups in the loop structure. The rapid inactivation of sAPX might be due to the characteristic conformation of Arg169 owing to the loop structure of sAPX. 相似文献
153.
Hashimoto M Sibata T Wasada H Toyokuni S Uchida K 《The Journal of biological chemistry》2003,278(7):5044-5051
4-Hydroxy-2-nonenal (HNE), a major racemic product of lipid peroxidation, reacts with histidine to form a stable HNE-histidine Michael addition-type adduct possessing three chiral centers in the cyclic hemiacetal structure. In the present study, we characterized configurational isomers of a HNE-N(alpha)-acetylhistidine adduct by NMR spectroscopy and by molecular orbital calculations. In addition, we raised monoclonal antibodies against (R)-HNE-histidine and (S)-HNE-histidine adducts, characterized their specificities, and examined in vivo localizations of each adduct under oxidative stress. To facilitate structural characterization of the configurational isomers of an HNE-histidine adduct, we prepared the (R)-HNE-histidine and (S)-HNE-histidine adducts by incubating N(alpha)-acetylhistidine with each HNE enantiomer, both of which provided two peaks (Ra and Rb from (R)-HNE-histidine and Sa and Sb from (S)-HNE-histidine adducts) in reversed-phase high-performance liquid chromatography. The NMR analysis showed that each peak was a mixture of two diastereomers. In addition, the analysis of the nuclear Overhauser effect enabled the determination of configurations of the eight isomers. The relative amounts of these isomers in the NMR analysis correlated with the relative energies calculated by molecular orbital methods. On the other hand, using (R)-HNE-modified and (S)-HNE-modified keyhole limpet hemocyanins as the antigens, we raised the monoclonal antibodies, mAbR310 and mAbS412, which enantioselectively recognized the (R)-HNE-histidine and (S)-HNE-histidine adducts, respectively. Among the mixtures (Ra, Rb, Sa, and Sb) of diastereomers, mAbR310 showed the highest immunoreactivity to Rb (the mixture of 2R,4S,5R and 2S,4S,5R isomers), whereas mAbS412 preferentially recognized Sa (the mixture of 2R,4S,5S and 2S,4S,5S isomers). The presence of (R)-HNE and (S)-HNE epitopes in vivo was immunohistochemically examined in the kidney of rats exposed to the renal carcinogen, ferric nitrilotriacetate, by which nuclear and cytosolic stainings with mAbR310 and mAbS412, respectively, were detected. 相似文献
154.
155.
Polymerase chain reactions with degenerate V gene segment primers were used to isolate the putative T-cell receptor alpha-chain gene (TCRA) from Japanese pufferfish (Takifugu rubripes). The putative TCRA chain cDNA is composed of an N-terminus leader peptide followed by the variable region and the constant region. The variable portion of the TCRA gene is encoded by V and J gene segments separated in the germline. As in mammals, the V-J junction sequences are GC rich and highly diversified. Amino acid residues that are required to maintain the function and structural integrity of the TCRA polypeptide, including the conserved Trp-Tyr-Lys and Tyr-Tyr-Cys motifs in the V gene segments, the Lys-Leu-X-Phe-Gly-X-Gly-Thr-X-Leu motif in the J gene segment, the three cysteine residues in the constant region and the charged residues in the transmembrane region are all preserved in the pufferfish. These conserved features suggest that the TCRA gene families in fish and mammals have evolved from a common ancestor. 相似文献
156.
A molecular marker diagnostic of a specific isolate of an arbuscular mycorrhizal fungus,Gigaspora margarita 总被引:1,自引:0,他引:1
To investigate the auto-ecology of a strain of Gigaspora margarita in a commercial inoculum, we found a pair of PCR primers amplifying a sequence of 235 bp diagnostic of the isolate. We designed an oligonucleotide probe based on the DNA sequence. The combination of PCR and the probing successfully detected the diagnostic sequence from both DNA preparations of single spores and colonized roots. This protocol enabled us to distinguish the isolate among several isolates from Japan, Nepal and the USA. 相似文献
157.
Weiping Qin Hong Luo Takahiro Nomura Naoyuki Hayashi Tatsuya Yamashita Seishi Murakami 《The Journal of biological chemistry》2002,277(3):2132-2137
HCV NS5B is an RNA-dependent RNA polymerase (RdRP), a central catalytic enzyme for HCV replication, which has the "palm and fingers" substructure. We recently identified five novel residues critical for RdRP activity (Qin, W., Yamashita, T., Shirota, Y., Lin, Y., Wei, W., and Murakami, S. (2001) Hepatology 33, 728-737). Among them, GLU-18 and His-502, far from the catalytic center, may be involved in conformational change(s) for RdRP activity as addressed in some palm and fingers enzymes. We examined the possibility that NS5B is oligomerized, and we could detect the interaction between two different tagged NS5B proteins in vitro and transiently expressed in mammalian cells. By scanning 27 clustered and then point alanine substitutions in vivo and in vitro, Glu-18 and His-502 were found to be critical for the homomeric interaction in vivo and in vitro, strongly suggesting a close relationship between the oligomerization and RdRP activity of NS5B. All mutants with substitutions at these two residues failed to bind wild type NS5B, however E18H interacted with H502E in vitro and in vivo. Interestingly, the NS5B protein with E18H or H502E did not exhibit RdRP activity, but a mixture of the two mutant proteins did. These results clearly indicate that two residues of HCV NS5B are critical for the oligomerization that is prerequisite to RdRP activity. 相似文献
158.
Furusawa M Taira T Iguchi-Ariga SM Ariga H 《The Journal of biological chemistry》2002,277(52):50885-50892
We have reported that a novel c-Myc-binding protein, AMY-1, binds to cAMP-dependent protein kinase-anchoring protein 149 (AKAP149) and its splicing variant, AKAP84 and is localized in the mitochondria in a complex with RII, a regulatory subunit of cAMP-dependent protein kinase (PKA) (Furusawa, M., Ohnishi, T., Taira, T., Iguchi-Ariga, S. M. M., and Ariga, H. (2001) J. Biol. Chem. 276, 36647-36651). In this study, we further found that AMY-1 competitively bound to either AKAP95 or AKAP84 in the nucleus and the cytoplasm, respectively, in a concentration-dependent manner of either AKAP. Like AKAP84, AMY-1 was found to bind to the RII-binding region of AKAP95 in vivo and in vitro and to make a ternary complex with RII. It was also found that the formation of the complex of AMY-1 with AKAP84/95 and RII prevented a catalytic subunit from binding to this AKAP complex, leading to suppression of PKA activity. These findings suggest that AMY-1 is an important modulator of PKA. 相似文献
159.
Identifying the transition between single and multiple mating of queens in fungus-growing ants 总被引:6,自引:0,他引:6
Villesen P Murakami T Schultz TR Boomsma JJ 《Proceedings. Biological sciences / The Royal Society》2002,269(1500):1541-1548
Obligate mating of females (queens) with multiple males has evolved only rarely in social Hymenoptera (ants, social bees, social wasps) and for reasons that are fundamentally different from those underlying multiple mating in other animals. The monophyletic tribe of ('attine') fungus-growing ants is known to include evolutionarily derived genera with obligate multiple mating (the Acromyrmex and Atta leafcutter ants) as well as phylogenetically basal genera with exclusively single mating (e.g. Apterostigma, Cyphomyrmex, Myrmicocrypta). All attine genera share the unique characteristic of obligate dependence on symbiotic fungus gardens for food, but the sophistication of this symbiosis differs considerably across genera. The lower attine genera generally have small, short-lived colonies and relatively non-specialized fungal symbionts (capable of living independently of their ant hosts), whereas the four evolutionarily derived higher attine genera have highly specialized, long-term clonal symbionts. In this paper, we investigate whether the transition from single to multiple mating occurred relatively recently in the evolution of the attine ants, in conjunction with the novel herbivorous 'leafcutter' niche acquired by the common ancestor of Acromyrmex and Atta, or earlier, at the transition to rearing specialized long-term clonal fungi in the common ancestor of the larger group of higher attines that also includes the genera Trachymyrmex and Sericomyrmex. We use DNA microsatellite analysis to provide unambiguous evidence for a single, late and abrupt evolutionary transition from exclusively single to obligatory multiple mating. This transition is historically correlated with other evolutionary innovations, including the extensive use of fresh vegetation as substrate for the fungus garden, a massive increase in mature colony size and morphological differentiation of the worker caste. 相似文献
160.
Carboxypeptidase Y (CPY) inhibitor, I(C), a yeast cytoplasmic inhibitor in which the N-terminal amino acid is acetylated, was expressed in Escherichia coli and produced as an unacetylated form of I(C) (unaI(C)). Circular dichroism and fluorescence measurements showed that unaI(C) and I(C) were structurally identical and produce identical complexes with CPY. However, the K(i) values for unaI(C) for anilidase and peptidase activity of CPY were much larger, by 700- and 60-fold, respectively, than those of I(C). The reactivities of phenylmethylsulfonyl fluoride and p-chloromercuribenzoic acid toward the CPY-unaI(C) complex were considerably higher than those toward the CPY-I(C) complex. Thus, the N-terminal acetyl group of I(C) is essential for achieving a tight interaction with CPY and for its complete inactivation. 相似文献