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11.
Hidetaka Kosako Yukiko Gotoh Eisuke Nishida 《Development, growth & differentiation》1996,38(6):577-582
Mitogen-activated protein kinase (MAPK) was originally identified as a serine/threonine protein kinase that is rapidly activated in response to various growth factors and tumor promoters in mammalian cultured cells. The kinase cascade including MAPK and its direct activator, MAPK kinase (MAPKK), is now believed to transmit various extracellular signals into their intracellular targets in eukaryotic cells. It has been reported that activation of MAPKK and MAPK occurs during the meiotic maturation of oocytes in several species, including Xenopus laevis . Studies with neutralizing antibodies against MAPKK, MAPK phosphatases and constitutively active MAPKK or MAPK have revealed a crucial role of the MAPKK/MAPK cascade in a number of developmental processes in Xenopus oocytes and embryos. 相似文献
12.
Lentinan, a -1,6;1,3-glucan, is tumor-specific for transplantable mouse solid-type tumors and it also stimulates the production of acute phase proteins (APPs). The APP response to lentinan is of the delayed type (DT-APR) and differs from that to lipopolysaccharide, which is acute. We found that the responses were genetically controlled in mice and that low responsiveness is dominant (Maeda et al. 1991). Using 123 segregants of crosses between SWR/J (a high responder) andMus spretus (a low responder), we analyzed the linkage between DT-APR responsiveness and the DNA polymerase chain reaction-simple sequence lenght polymorphism (PCR-SSLP) phenotype using 80 chromosome-specific microsatellite markers. We identified two loci (ltn1.1 andltn1.2) responsible for DT-APR.ltn1.1 is closely linked toD3Mit11 on chromosome 3 andltn1.2 toD11Nds9 on chromosome 11 (P<0.001). The linkage analysis also suggested thatltn1.2 is the major determinant for DT-APR. Correlation between lentinan-specific IL-6 mRNA expression (the late expression) controlled recessively and DT-APR induction suggests that theltn1 loci control some process(es) of IL-6 expression in the regulation step before NF-IL6. 相似文献
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Kazuo Yamamoto Chizu Ishida Mitsue Saito Yukiko Konami Toshiaki Osawa Tatsuro Irimura 《Glycoconjugate journal》1994,11(6):572-575
Maackia amurensis haemagglutinin (MAH) is a leguminous lectin which preferentially binds to a cluster of sialylatedO-linked carbohydrate chains (Konami Y, Yamamoto K, Osawa T, Irimura T (1994)FEBS Lett
342:334–38). In the present study a 950 bp cDNA clone encoding MAH was isolated from a cDNA library constructed from germinatedMaackia amurensis seeds. From the nucleotide sequence, MAH was predicted to consist of 285 amino acid residues containing a signal peptide of 29 amino acids. The results also confirmed our previous findings from the amino acid sequence analysis, which indicated that two highly conserved amino acid residues in all other well-known leguminous lectins were replaced in MAH. These residues were lysine-105 and aspartic acid-135. The corresponding amino acid residues in other leguminous lectins were glycine and asparagine, respectively. These differences were due to the presence of nucleotides AAA and GAT in place of AAT/C and GGA/T.Abbreviations MAH
Maackia amurensis haemagglutinin. 相似文献
15.
Antioxidant Properties of Bromocriptine, a Dopamine Agonist 总被引:3,自引:1,他引:2
Toshikazu Yoshikawa† Yukiko Minamiyama Yuji Naito Motoharu Kondo 《Journal of neurochemistry》1994,62(3):1034-1038
Abstract: It has been suggested that free radicals may adversely influence the pathogenesis of Parkinson's disease. We conducted this study to determine whether bro-mocriptine, an agent widely used for treating parkinsonism, possesses antioxidant effects. Bromocriptine scavenged superoxide produced from a superoxide generating system (hypoxanthine-xanthine oxidase) by the spin-trapping method using electron spin resonance. Bromocriptine had a strong scavenging effect on the 5,5-dimethyl-1-pyrroline- N -oxide hydroxide signal produced from Fenton's reaction. Bromocriptine also attenuated the stable free radical diphenyl- p -picrylhydrazyl signal. This drug inhibited the autooxidation of rat brain homogenates in a dose-dependent manner in vitro. Autooxidation of brain homogenates collected from rats treated with bromocriptine (2.5 mg/kg, i.p., daily for 3 days) was significantly reduced as compared with values in untreated rat homogenates. These observations suggest that bromocriptine is a free radical scavenger and a potent antioxidant. 相似文献
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Sakamoto Atsushi; Ohsuga Hiroyuki; Wakaura Makoto; Mitsukawa Norihiro; Hibino Takashi; Masumura Takehiro; Sasaki Yukiko; Tanaka Kunisuke 《Plant & cell physiology》1993,34(6):965-968
A cDNA clone for copper/zinc-superoxide dismutase (Cu/Zn-SOD)was isolated from spinach (Spinacia oleracea L.) leaves. Itsnucleotide sequence showed that it codes for a precursor polypeptideof 222 amino acids, including the NH2-terminal 68-residue extensionwhich corresponds to a plastidic transit peptide. Northern hybridization,using plastidic and cytosolic Cu/Zn-SOD cDNAs as the probes,revealed that these two genes are differentially expressed inthe roots and leaves of spinach.
1Present address: Department of Biochemistry and Microbiology,Cook College, Rutgers University New Brunswick, NJ 08903-0231,U.S.A. 相似文献
18.
Yoshio Osawa Tadayoshi Higashiyama Yukiko Shimizu Carol Yarborough 《The Journal of steroid biochemistry and molecular biology》1993,44(4-6):469-480
Androgen aromatase was found to also be estrogen 2-hydroxylase. The substrate specificity among androgens and estrogens and multiplicity of aromatase reactions were further studied. Through purification of human placental microsomal cytochrome P-450 by monoclonal antibody-based immunoaffinity chromatography and gradient elution on hydroxyapatite, aromatase and estradiol 2-hydroxylase activities were co-purified into a single band cytochrome P-450 with approx. 600-fold increase of both specific activities, while other cytochrome P-450 enzyme activities found in the microsomes were completely eliminated. The purified P-450 showed Mr of 55 kDa, specific heme content of 12.9 ± 2.6 nmol·mg−1 (±SD, N = 4), reconstituted aromatase activity of 111 ± 19 nmol·min−1·mmg−1 and estradiol 2-hydroxylase activity of 5.85 ± 1.23 nmol·min−1·mg−1. We found no evidence for the existence of catechol estrogen synthetase without concomitant aromatase activity. The identity of the P-450 for the two different hormone synthetases was further confirmed by analysis of the two activities in the stable expression system in Chinese hamster ovarian cells transfected with human placental aromatase cDNA, pH β-Aro. Kinetic analysis of estradiol 2-hydroxylation by the purified and reconstituted aromatase P-450 in 0.1 M phosphate buffer (pH 7.6) showed Km of 1.58 μM and Vmax of 8.9 nmol·min−1·mg−1. A significant shift of the optimum pH and Vmax, but not the Km, for placental estrogen 2-hydroxylase was observed between microsomal and purified preparations. Testosterone and androstenedione competitively inhibited estradiol 2-hydroxylation, and estrone and estradiol competitively inhibited aromatization of both testosterone and androstenedione. Estrone and estradiol showed Ki of 4.8 and 7.3 μM, respectively, for testosterone aromatization, and 5.0 and 8.1 μM, respectively, for androstenedione aromatization. Androstenedione and testosterone showed Ki of 0.32 and 0.61 μM, respectively, for estradiol 2-hydroxylation. Our studies showed that aromatase P-450 functions as estrogen 2-hydroxylase as well as androgen 19-, 1β-,and 2β-hydroxylase and aromatase. The results indicate that placental aromatase is responsible for the highly elevated levels of the catechol estrogen and 19-hydroxyandrogen during pregnancy. These results also indicate that the active site structure holds the steroid ssubstrates to face their β-side of the A-ring to the heme, tilted in such a way as to make the 2-position of estrogens and 19-, 1-, and 2-positions of androgens available for monooxygenation. 相似文献
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Stereospecific Reduction of Ethyl 2′ -Ketopantothenate to Ethyl D-(+)-Pantothenate with Microbial Cells as a Catalyst 下载免费PDF全文
Michihiko Kataoka Sakayu Shimizu Yukiko Doi Hideaki Yamada 《Applied microbiology》1990,56(11):3595-3597
A novel enzymatic process for the synthesis of D-(+)-pantothenic acid through the asymmetric reduction of the 2′ -ketopantothenate ester is described. Candida macedoniensis AKU 4588 was found to convert ethyl 2′ -ketopantothenate (80 mg/ml) almost specifically to ethyl D-(+)-pantothenate (>98% enantiomeric excess), with a molar yield of 97.2%. 相似文献