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51.
Kaoru Miyazaki Keisuke Mashima Nobuhiko Yamashita Jinpei Yamashita Takekazu Horio 《In vitro cellular & developmental biology. Plant》1985,21(1):62-66
Summary We have previously reported the transformation by Rous sarcoma virus of a cloned epithelial cell line (BRL) established from
Buffalo rat liver by H. Coon. The nontransformed (BRL) and transformed (RSV-BRL) cells grew at comparable rates in culture,
whereas only the transformed cells were tumorigenic in vivo. We report here on the existence in rat and mouse sera of a growth
inhibitor for the nontransformed BRL cells. The transformed BRL cells (RSV-BRL) were insensitive to this inhibitor. The inhibitory
activity was not prominent in sera from other species of animals tested except for rabbit; this serum inhibited the growth
of RSV-BRL cells more strongly than that of BRL cells. The growth inhibitor was partially purified from rat serum. It is a
protein free of lipid and has a molecular weight of about 220 000. The inhibitor could be separated into three components
of pI 4.6, 5.2 (major) and 5.6 by isoelectric electrophoresis.
EDITOR'S STATEMENT Although compelling theoretical arguments sometimes can be made for the likely existence of growth-inhibitory
substances of physical relevance in the control of cell proliferation, experiments aimed at identifying and studying such
factors often are difficult to design and interpret, and little strong data exists to suggest that growth-inhibitory substances
are important regulatorsin vivo. The information presented in this paper represents a start toward developing a useful system for studying growth-inhibitory
factor. David W. Barnes 相似文献
52.
Dov Borovsky 《Archives of insect biochemistry and physiology》1985,2(2):145-159
Proteolytic enzymes were characterized in the midgut and the excreta of the stable fly Stomoxys calcitrans (L) with proteins, synthetic substrates, and inhibitors. Inhibition studies suggested trypsinlike activity in sugar-fed fly midguts, whereas excreta and blood-fed fly guts exhibited other proteases. Trypsinlike activity in midguts removed 20 and 30 h after a blood meal increased from 20% to 50% of the total proteolytic enzymes present. Trypsinlike activity was inhibited with human sera, trypsin-specific inhibitors, and a protein isolated from the stable fly thorax. When human albumin and globulin fractions were incubated with trypsinlike enzymes isolated from the midgut and excreta, the albumin fraction was less inhibitory than the globulin fractions and was readily hydrolyzed by the proteolytic enzymes. These results may indicate that the proteolytic enzymes produce an abortive complex with the globulin fractions of the sera. Such a complex may explain the temporary inhibition of proteolysis by the blood meal. Soybean trypsin inhibitor fed to stable flies caused 50% inhibition in proteolytic activity in the midguts of sugar-fed stable flies and 25% inhibition in the midguts of blood-fed stable flies. Complete inhibition of proteolytic enzyme activity was achieved only in vitro. pH profiles of proteolytic enzyme activity isolated from the excreta of blood-fed stable flies indicated that several proteolytic enzymes were excreted. 相似文献
53.
Insulin (100 U/ml) stimulated protein synthesis and PGF2 release in isolated rabbit muscle, but had little effect on the rate of protein degradation. The effect of insulin persisted for at least 5 h after removal of the hormone. Indomethacin, added at the start of the incubation, inhibited the stimulatory effect of insulin on protein synthesis and PGF2 release, but did not block the binding of iodinated insulin. When added 2 h after insulin, indomethacin did not inhibit the stimulation of protein synthesis but completely inhibited the increase in PGF2 release. The results suggest that the stimulation of protein synthesis by insulin is mediated by metabolites of membrane phospholipids but that these changes are involved during the phase of response that immediately follows the binding of insulin to its receptor. 相似文献
54.
Nobuo Aoki 《Journal of Protein Chemistry》1986,5(4):269-277
Fibrinolytic system is one of the major proteolytic pathways in vivo and primarily responsible for dissolution of thrombi. Two enzymes are primarily involved in this proteolytic system; plasminogen activator (PA) and plasmin. Plasmin is formed by a limited proteolysis of plasminogen by PA, which is mainly synthesized by and secreted from vascular endothelial cells. This proteolytic process proceeds physiologically only on the surface of fibrin. Thus, initiation and progression of the fibrinolytic process depend on the function of endothelial cells and fibrin formation. Endothelial cells may also synthesize and excrete PA inhibitor (PAI) which inhibits immediately, PA once released. The rates of synthesis and excretion of PA and PAI by endothelial cells are regulated by various factors. Among them, thrombin stimulates the release of PA whereas activated protein C may decrease the release of PAI. Thus, both enzymes enhance fibrinolytic potential. PA which has escaped from inhibition by PAI binds to fibrin. 2-Plasmin inhibitor (2PI) inhibits the binding of plasminogen to fibrin, thereby suppressing this fibrin-associated plasminogen activation. A part of 2PI is cross-linked to fibrin by activated factor XIII when fibrin is formed, and the 2PI thus cross-linked to fibrin inhibits in situ plasmin formed on fibrin. Thus, 2PI as well as PAI plays a central role in inhibition of fibrinolysis. 相似文献
55.
Selective expression of a probable amylase/protease inhibitor in barley aleurone cells: Comparison to the barley amylase/subtilisin inhibitor 总被引:5,自引:0,他引:5
We have cloned and sequenced a 650-nucleotide cDNA from barley (Hordeum vulgare L.) aleurone layers encoding a protein that is closely related to a known -amylase inhibitor from Indian finger millet (Eleusine coracana Gaertn.), and that has homologies to certain plant trypsin inhibitors. mRNA for this probable amylase/protease inhibitor (PAPI) is expressed primarily in aleurone tissue during late development of the grain, as compared to that for the amylase/subtilisin inhibitor, which is expressed in endosperm during the peak of storage-protein synthesis. PAPI mRNA is present at high levels in aleurone tissue of desiccated, mature grain, and in incubated aleurone layers prepared from rehydrated mature seeds. Its expression in those layers is not affected by either abscisic acid or gibberellic acid, hormones that, respectively, increase and decrease the abundance of mRNA for the amylase/subtilisin inhibitor. PAPI mRNA is almost as abundant in gibberellic acid-treated aleurone layers as that for -amylase, and PAPI protein is synthesized in that tissue at levels that are comparable to -amylase. PAPI protein is secreted from aleurone layers into the incubation medium.Abbreviations ABA
abscisic acid
- ASI
barley amylase/subtilisin inhibitor
- bp
nucleotide base pairs
- Da
dalton
- dpa
days post anthesis
- GA3
gibberellic acid
- PAPI
probable amylase/protease inhibitor
- poly(A)RNA
polyadenylated RNA
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis 相似文献
56.
Specific protein inhibitors of microbial serine proteinases were isolated from wheat (Triticum aestivum L.), rye (Secale cereale L.) and triticale using affinity chromatography on subtilisin-Sepharose 4B. The wheat inhibitor had an isoelectric point (pI) at pH 7.2, while the rye inhibitor consisted of two forms with pI values of 6.8 and 7.1. In triticale, two components were present with pIs 7.2 and 6.8. All the inhibitors had M
r values of approx. 20 000. The isolated proteins were effective inhibitors of subtilisins Carlsberg and BPN, and of fungal proteinases (EC 3.4.21.14) from the genus Aspergillus, but they were completely inactive against trypsin (EC 3.4.21.4) chymotrypsin (EC 3.4.21.1) and pancreatic elastase (EC 3.4.21.36). The inhibitors formed complexes with subtilisin in a molar ratio of 1:1. The results of chemical modifications seem to indicate that the isolated inhibitors have methionine residues in their reactive sites.Abbreviation pI
isoelectric point 相似文献
57.
Fragments derived from human plasma fibronectin by enzymatic degradation were tested in the Boyden chamber for chemotactic activity towards various fibroblast strains. The results provide clear evidence that the chemotactic activity is restricted to a defined region of the fibronectin molecule which is the same for various fibroblast strains. The active domain is localized between the collagen binding site and the major heparin binding site, about 170 kDa apart from the N-terminal and about 70 kDa from the C-terminal ends of the two subunit peptide chains. 相似文献
58.
Bromo[1-14C]acetyl-CoA has been prepared from CoASH and the N-hydroxysuccinimide ester of bromo[1-14C]acetic acid, and unlabeled bromoacetyl-CoA by reaction of CoASH with bromoacetyl bromide. The products were purified by high-pressure liquid chromatography. Purified bromoacetyl-CoA was characterized, and found to be a potent alkylating agent with a substantial stability in aqueous solution: it decomposed at 30 degrees C and pH 6.6 and 8.0 with halftimes of 3.3 and 2.5 h, respectively. The major breakdown products were CoASH and CoAS X CO X CH2 X SCoA. Bromo[1-14C]acetyl-CoA has been used to affinity label the acetyl-CoA binding site of 3-hydroxy-3-methylglutaryl-CoA synthase from ox liver. It was found to irreversibly inhibit the enzyme activity and bind covalently with a stoichiometry for complete inhibition of about 0.8 mol/mol enzyme dimer. 相似文献
59.
The different isomers of the dipeptide beta-N-gamma-glutamyl diaminopropionate inhibit L-glutamate-1-carboxylyase (GAD, EC-4.1.1.15) activity in mouse brain homogenates. The L-D isomer is the most effective as an inhibitor, while the D-D isomer is least inhibitory. The different isomers are neurotoxic to mice and the chick, the L-D isomer being the most toxic. The neurotoxicity of the isomers in mice was also associated with a significant lowering in GAD activity in the brains of convulsing mice. 相似文献
60.
A neutral growth inhibitor, isolated from methanolic extracts of sunflower seedlings, was characterized by spectral data as caprolactam. Light-grown se 相似文献