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21.
An insulin-stimulated ribosomal protein S6 kinase from rabbit liver 总被引:14,自引:0,他引:14
J S Gregory T G Boulton B C Sang M H Cobb 《The Journal of biological chemistry》1989,264(31):18397-18401
In this report we describe an activated form of S6 protein kinase in rabbits treated acutely with insulin. The major insulin-stimulated activity in rabbit liver is increased 2- to 5-fold compared to material from untreated animals based on DEAE-cellulose profiles. The activity observed in DEAE-cellulose fractions can be separated into a major and a minor peak, each having very similar chromatographic behavior. Chromatography on DEAE-cellulose, S-Sepharose, heptyl-Sepharose, heparin-agarose, and Mono Q results in greater than 20,000-fold purification of the insulin-stimulated enzyme with a 12% recovery. The stimulated activity has chromatographic properties similar to an S6 protein kinase studied previously in 3T3-L1 cells (Cobb, M. H. (1986) J. Biol. Chem. 261, 12994-12999) and other systems. The enzyme purified from insulin-treated animals contains a major band that migrates in sodium dodecyl sulfate-polyacrylamide gels with Mr congruent to 70,000; this band also appears in the control preparation. Treatment of the insulin-stimulated S6 kinase with the catalytic subunit of phosphatase 2a reduces its activity by 97%. The activity of the inactivated S6 kinase is stimulated nearly 5-fold by a 15-min preincubation with partially purified insulin-stimulated microtubule-associated protein-2 kinase. 相似文献
22.
E T Koh 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1990,194(2):108-113
The purpose of this study was to determine what levels of starch or glucose replacement for fructose in the copper-deficient diet (copper) can minimize the fructose-copper interaction. Experimental diets contained either 100% fructose as the carbohydrate source, or the fructose was partially replaced with 50% starch, 50% glucose, 75% starch, or 75% glucose. Diets were either copper adequate (7-8 ppm) or inadequate (less than 1 ppm). Male weanling rats were fed their respective diet for 5 weeks and then fasted overnight. After decapitation, blood was collected and liver and heart were removed. Plasma copper was significantly reduced and ceruloplasmin was not detected in all copper-deficient groups. Copper deficiency increased plasma cholesterol, as well as heart and liver weight in the glucose groups, but not in the starch groups. Those organ weights were heavier in glucose-copper than starch-copper rats. Erythrocyte copper-zinc-superoxide dismutase activity was greater in starch-copper rats. Erythrocyte copper-zinc-superoxide dismutase activity was greater in starch-copper than glucose-copper rats regardless of carbohydrate amount. Hepatic copper concentration of the group fed starch-copper was twice levels observed in glucose-copper. The 50% glucose rats had lower hepatic copper than the 75% glucose rats. Hepatic copper-zinc-superoxide dismutase activity showed patterns similar to hepatic copper. Cardiac copper was greater in starch-copper than glucose-copper rats. Cardiac copper-zinc-superoxide dismutase activity was equally reduced in all copper-deficient groups. The 50% starch-replaced diet was more effective in minimizing copper deficiency than the 75% glucose-replaced diet. This poorer improvement of copper deficiency by glucose than starch may partially be due to a more severe reduction of food intake in glucose than in starch diets. 相似文献
23.
Computational sequence analysis of matrix metalloproteinases 总被引:12,自引:0,他引:12
Matrix metalloproteinases (MMP) play a cardinal role in the breakdown of extracellular matrix involved in a variety of biological and pathological processes. Research on MMPs has classified and characterized these enzymes according to their matrix substrate specificity, gene and protein domain structure, and regulation of activity and expression. However, the discovery of new MMPs has introduced a need for a more comprehensive and systematic method of classification and quantitative comparison of known and newly discovered members. This study compiles a sequence alignment, constructs a dendrogram, and calculates physical data and homology percentage assignments in order to obtain further insight into MMP structure-function relationships. Thorough analysis of MMP primary sequence domains, physical data patterns, and statistical analysis of sequence homology yields higher resolution in the similarities and differences that group MMP members. 相似文献
24.
Summary Cell growth increased proportionally to the initial concentration of ammonium ion, however, methylan production was significantly inhibited at the high concentration of ammonium ion. The control of ammonium ion within the desired level(usually 0.45 g/l) was needed to reduce the inhibition. Methylan production was increased to 12.5 g/l by maintaining ammonium ion below 0.15 g/l. 相似文献
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26.
Trienoic fatty acids, namely -linolenic acid and hexadecatrienoic acid, present in leaf lipids are produced by -3 fatty acid desaturases located in the endoplasmic reticulum and plastid membranes. The changes in the level of trienoic fatty acids during leaf maturation were investigated in wild-type plants of Arabidopsis thaliana (L.) Heynh. and in the fad7 mutant deficient in the activity of a plastid -3 desaturase. The levels of trienoic fatty acids increased in 26 °C- and 15 °C-grown wild-type plants with maturation of leaves. The increase in trienoic fatty acids was mainly due to galactolipids enriched in plastid membranes. In addition, the relative levels of trienoic fatty acids in major glycerolipids, including phospholipids enriched in the endoplasmic reticulum membranes, also increased with leaf maturation. By contrast, when the fad7 mutant was grown at 26 °C, the relative levels of trienoic fatty acids in individual lipids decreased with leaf maturation. The decreases in the levels of trienoic fatty acids, however, were alleviated when the fad7 mutant was grown at 15 °C. These results suggest that the plastid -3 desaturase plays a major role in increasing the levels of trienoic fatty acids with leaf maturation.Abbreviations 163
hexadecatrienoic acid
- 183
-linolenic acid
- DGD
digalactosyldiacylglycerol
- MGD
monogalactosyldiacylglycerol
- PC
phosphatidylcholine
- PE
phosphatidylethanolamine
- TA
trienoic fatty acid
- WT
wild type
- -3
refers to the position of the double bond from the methyl end of a fatty acid
This research was supported in part by Grants-in-Aid for Scientific research (#07251214 and #06804050 to K.I.) from the Ministry of Education, Science and Culture, Japan, and by the research grant from Shorai Foundation. 相似文献
27.
28.
Genetic exchange in soil between introduced chlorobenzoate degraders and indigenous biphenyl degraders. 总被引:2,自引:0,他引:2
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Pseudomonas aeruginosa JB2, a chlorobenzoate degrader, was inoculated into soil having indigenous biphenyl degraders but no identifiable 2-chlorobenzoate (2CBa) or 2,5-dichlorobenzoate (2,5DCBa) degraders. The absence of any indigenous chlorobenzoate degraders was noted by the failure to obtain enrichment cultures with the addition of 2CBa, 3CBa, or 2,5DCBa and by the failure of soil DNA to hybridize to the tfdC gene, which encodes ortho fission of chlorocatechols. In contrast, DNA extracted from inoculated soils hybridized to this probe. Bacteria able to utilize both biphenyl and 2CBa as growth substrates were absent in uninoculated soil, but their presence increased with time in the inoculated soils. This increase was related kinetically to the growth of biphenyl degraders. Pseudomonas sp. strain AW, a dominant biphenyl degrader, was selected as a possible parental strain. Eight of nine recombinant strains, chosen at random, had high phenotypic similarity (90% or more) to the inoculant; the other, strain JB2-M, had 78% similarity. Two hybrid strains, P. aeruginosa JB2-3 and Pseudomonas sp. JB2-M, were the most effective of all strains, including strain AW, in metabolizing polychlorinated biphenyls (Aroclor 1242). Repetitive extragenic palindromic-PCR analysis of putative parental strains JB2 and AW and the two recombinant strains JB2-3 and JB2-M showed similar fragments among the recombinants and JB2 but not AW. These results indicate that the bph genes were transferred to the chlorobenzoate-degrading inoculant from indigenous biphenyl degraders. 相似文献
29.
Rebamipide, a novel antipeptic ulcer drug, 2-(4-chlorobenzoylamino)-3-[2(1H)-quinolinone-4-yl]-propionic acid, was studied for its inhibitory effect on gastric xanthine oxidase activity and type conversion of the enzyme that has a profound role in free radical generation. Intraperitoneal administration of rebamipide at 60 mg/kg body weight reduced gastric mucosal hemorrhagic lesions and lipid peroxidation, which was proportional to the inhibitory effect of rebamipide on alcohol-induced xanthine oxidase-type conversion and enzyme activity. It was also observed that the activity of xanthine oxidase was significantly inhibited by administration of rebamipide at 60 mg/kg body weight, leading to a significant reduction of lipid peroxide content in alcohol-treated rats. The results suggest that alcohol-induced gastric mucosal lesions might be, in part, due to the increased activity of xanthine oxidase and type conversion rate of the enzyme and the protective effect of rebamipide on gastric mucosal lesions would result from its ability to protect against oxidative stress on gastric mucosal lesions of alcohol-treated rats. 相似文献
30.
本工作将富集小鼠着丝粒DNA克隆于载体EMBL3,得到约2000个克隆,建立了着丝粒基因文库。从中随机挑取20个克隆,鉴定其克隆片段平均分子量大小约为14kb。 相似文献