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31.
Interleukin 2 (IL 2) is a polypeptide growth factor essential for the proliferation and differentiation of T lymphocytes, large granulocytic lymphocytes, and, potentially, cells of the antibody-producing lineage, B lymphocytes. Many of the biological properties of IL 2 may be mimicked or potentiated by a potent class of tumor promoters, phorbol esters. Phorbol esters have recently been shown to associate with and activate a unique phospholipid/Ca2+-dependent phosphotransferase, protein kinase C (PK-C). Utilizing two-dimensional gel electrophoresis, we have compared the IL 2 and diacylglycerol-induced protein phosphorylation patterns of several IL 2-dependent murine cell lines. Both IL 2 and synthetic diacylglycerol, 1-oleyl-2-acetylglycerol (OAG), stimulated phosphorylation of a number of protein substrates in intact cells compared to unstimulated controls. Three groups of substrates were identified; the first showed increased phosphorylation following stimulation with either IL 2 or OAG, while the second and third groups showed increased phosphorylation following stimulation with IL 2 but not OAG, and with OAG but not IL 2, respectively. Here, we characterize the kinetics of phosphorylation of one cellular substrate, p68, which appears to be phosphorylated in response to direct activators of PK-C or lymphoid or myeloid growth factors in their respective lineage cell lines. The observation that IL 2 also stimulates a unique series of phosphoproteins in addition to those induced by direct PK-C activators suggests that IL 2 may initiate additional protein kinase activities, unrelated to PK-C, which may also be critical for the ligand-receptor signal transduction process regulating growth and gene expression. 相似文献
32.
Cholesterylphosphoryldimethylethanolamine is a zwitterionic compound which is a good bilayer stabilizer. As has been found with many other compounds having these properties, cholesterylphosphoryldimethylethanolamine is found to be a potent inhibitor of protein kinase C in both vesicle and micelle assay systems. The kinetics of the inhibition in Triton X-100 micelles was non-competitive with respect to ATP, histone, diolein, phorbol ester and Ca2+. It has a Ki of about 30 m. The inhibition kinetics as a function of phosphatidylserine concentration is more complex but suggestive of competitive inhibition. Cholesterylphosphoryldimethylethanolamine does not prevent the partitioning of protein kinase C into the membrane. This inhibitor lowers the Ca2+-phosphatidylserine-independent phosphorylation of protamine sulfate by protein kinase C and directly affects the catalytic segment of the enzyme generated by tryptic hydrolysis. Thus, this zwitterionic bilayer stabilizing inhibitor of protein kinase C both competes with the binding of phosphatidylserine as well as affects the active site of protein kinase C.Abbreviation CPD
cholesterylphosphoryldimethylethanolamine 相似文献
33.
L. M. Popescu C. Cernescu I. I. Moraru St. N. Constantinescu F. Baltã M. Manciulea E. Brãiloiu L. Buzilã 《Bioscience reports》1989,9(5):531-539
A monospecific inhibitory antibody directed to phospholipase C (phosphoinositidase C) blocked the antiviral effect of human interferons alpha and beta when tested on human quiescent fibroblasts challenged with the vesicular stomatitis virus. This action was due to specific inhibition of polyphosphoinositide hydrolysis because (a) the F(ab)2 fragment of the antibody molecule was also inhibitory; (b) excess antibodies directed to phospholipase A2 and to a phosphatidylcholine-preferring phospholipase C did not have any inhibitory effect, and (c) the combination of 12-O-tetradecanoylphorbol-acetate and calcium ionophore A23187 had an interferon-like antiviral effect which was not influenced by the inhibitory anti-phospholipase C antibodies. To avoid an interferon-like effect due to induction of interferon by second messengers, Vero cells, which lack interferon biosynthesis, were also used. Liposomes containing inositol 1,4,5-triphosphate and 1-oleoyl-2-acetyl-rac-glycerol protected Vero cells against the infection with the vesicular stomatitis virus. These results taken together show that phosphoinositide-derived second messengers are involved in triggering the antiviral effect of interferons alpha and beta. 相似文献
34.
The intracellular pH of the halotolerant green algae Dunaliella tertiolecta, was determined by the distribution of 5,5-dimethyl-2(14C)-oxalolidine-2,5-dione (DMO) between the cell and the surrounding medium. 5,5-dimethyl-2(14C)oxalolidine-2,4-dione was not metabolized by the algal cells. The intracellular pH of Dunaliella tertiolecta was 6.8 in the dark and 7.4 in the light. During a salt stress, after two hours, the intracellular pH was increased by 0.2 pH units in both light and dark. The salt stressed cells maintained a constant pH of about 7.5 over the pH range of 6.5 to 8.5. Because of the relatively low permeability coefficient of the plasma membrane for DMO, this technique does not permit rapid pH determinations during the induction period after a salt stress. The magnitude of the salt induced pH changes measured 2 h after the salt stress implies a minor importance of this alkalization in this time range, but does not exclude a larger importance of pH changes for osmoregulation during the induction period.Abbreviations Chl
chlorophyll
- DMO
5,5-dimethyl-2(14C)oxalolidine-2,4-dione
- PCV
packed cell volume
- SDS
sodium dodecyl sulfate 相似文献
35.
Purification and some properties of the methyl-CoM reductase of Methanothrix soehngenii 总被引:1,自引:0,他引:1
Mike S.M. Jetten Alfons J.M. Stams Alexander J.B. Zehnder 《FEMS microbiology letters》1990,66(1-3):183-186
Abstract The methyl-CoM reductase from Methanothrix soehngenii was purified 18-fold to apparent homogeneity with 50% recovery in three steps. The native molecular mass of the enzyme estimated by gel-fitration was 280 kDa. SDS-polyacrylamide gel electrophoresis revealed three protein bands corresponding to M r 63 900, 41 700 and 30 400 Da. The methyl-coenzyme M reductase constitutes up to 10% of the soluble cell protein. The enzyme has K m apparent values of 23 μM and 2 mM for N -7-mercaptoheptanoylthreonine phosphate (HS- HTP = component B ) and methyl-coenzyme M (CH3 CoM) respectively. At the optimum pH of 7.0 60 nmol of methane were formed per min per mg protein. 相似文献
36.
Calluses induced fromPterocladia capillacea have been kept in culture for more than three years. They exhibit a fast growth rate, owing to the release of single cells, which in turn develop into new callus. The effect of various media and culture conditions upon growth was investigated. In order to confirm the identity of the callus cells, a 0,45 mg incoculum was grown that yielded 15 g dried callus within six weeks. Polysaccharides from this material (5.5 g) were analysed by13C NMR spectroscopy. This produced a spectrum typical of agar and very similar to the one obtained for agar extracted fromP. capillacea plants. However, the callus agar displayed no gel-forming properties, even after alkali modification.author for correspondence 相似文献
37.
Kunio Yonemasu Takako Sasaki Yoshiko Dohi Charles M. Lapière Betty Nusgens 《生物化学与生物物理学报:疾病的分子基础》1990,1096(1):47-51
C1q, a collagen-like complement protein, was purified from the serum of a ddermatosparactic calf which lacks procollagen N-terminal proteinase (pN-proteinase). The specific hemolytic activity of the serum Clq from the dermatosparactic animal was identical to that of C1q from a normal calf. Gel-filtration of serum from dermatosparactic calf, on Sepharose 6B, showed the presence of C1q-antigenic material at only one position which was identical to the elution position of normal bovine C1q. No differdence, under dissociating conditions, could be seen in the size of the chains of C1q in specific immunoprecipitates isolated from the sera of dermatosparactic and normal animals, as judged by polyacrylamidegel electrophoresis (PAGE) in the presence of sodium dodecyl sulfate (SDS). The C1q from the dermatosparactic animal showed the same N-terminal amino acid and typtic-digest peptide pattern on HPLC as C1q from the normal calf. These results strongly suggest that pN-proteinase is not involved in the extracellular processing of C1q. 相似文献
38.
Summary The actions of cyclic AMP are subject to several levels of post-receptor modulation in cardiac tissue. Isoproterenol and prostaglandin E1 both stimulate cAMP accumulation, but only isoproterenol causes activation of particulate cAMP-dependent protein kinase, leading to activation of phosphorylase kinase and glycogen phosphorylase, and inhibition of glycogen synthase. Through the use of isolated, adult ventricular myocytes, we have determined that the hormone-specific activation of glycogen phosphorylase is due to subcellular compartmentation of cAMP. There is some evidence that cyclic nucleotide phosphodiesterases, whose activity is stimulated by alpha1-adrenergic agonists in isolated myocytes, may have a role in compartmentation. Phosphoinositide hydrolysis is stimulated by alpha, and muscarinic agonists, presumably leading to activation of protein kinase C, which in turn has multiple effects on hormone-sensitive adenylate cyclase.Abbreviations cAMP
Adenosine-3,5-Cyclic Monophosphate
- cGMP
Guanosine-3,5-Cyclic Monophosphate
- Gi, GS
Guanine nucleotide-binding proteins linked to inhibition and stimulation, respectively, of adenylate cyclase
- GTP
Guanosine-5-triphosphate
- PDE
Cyclic Nucleotide Phosphodiesterase
- PGE1
Prostaglandin E1 相似文献
39.
40.
Lithium Stimulation of Membrane-Bound Phospholipase C from PC 12 Cells Exposed to Nerve Growth Factor 总被引:4,自引:4,他引:0
LiCl stimulated the formation of inositol monophosphate in PC12 cells that had been exposed to nerve growth factor (NGF) for 4-5 days. Half-maximal accumulation was observed at approximately 8 mM LiCl. Stimulation of formation of inositol bisphosphate plus inositol trisphosphate was half-maximal at approximately 1 mM LiCl. With membranes isolated from PC12 cells differentiated with NGF, the hydrolysis of added phosphatidylinositol 4,5-bisphosphate (PIP2) was stimulated by LiCl in a biphasic manner, with the first stimulation half-maximal at approximately 0.7 mM and the second half-maximal at approximately 15 mM LiCl. The apparent Km for PIP2 was lowered in the presence of 1.1 mM LiCl from approximately 200 to approximately 70 microM. Membranes from cells grown in the absence of NGF did not respond to LiCl. Although observations with intact cells are difficult to interpret without ambiguity, the results obtained with isolated membranes support our interpretation of the stimulatory action of lithium in the intact PC12 cells. 相似文献