Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cellular retinol-binding protein (cRBP) and cellular retinoic acid-binding protein (cRABP) were purified from calf liver and uterus, respectively. Soluble Ca+2- phosphatidylserine-dependent protein kinase-C (PK-C) derived from mouse brain was capable of phosphorylating both of these apoproteins in vitro as determined by the phosphocellulose binding assay. The Km value was determined to be 6.2 microM for apo-cRBP and 5.1 microM for apo-cRABP. In contrast, the Km value for the histone III-S fraction was estimated to be 10.8 microM; the Km values for ATP in the presence of apo-cRBP and apo-cRABP were 12.4 microM and 2.6 microM, respectively. Specificity of phosphorylation of the retinoid-binding proteins was confirmed by polyacrylamide gel electrophoresis and subsequent autoradiography of the assay mixture as well as by a concentration-dependent, Ca+2, and phosphatidylserine sensitivity of the phosphorylation of both apo-cRBP and apo-cRABP. Inhibition of PK-C activity by holo-cRBP and holo-cRABP was also observed. Thus, phosphorylation of both of the retinoid-binding proteins may play an important modulating role in i) the ability of retinoids to function as antipromoters in chemically-induced tumorigenesis and ii) the control of physiological aspects of retinoid action in normal and retrodifferentiated cells.
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PMID:Retinoid-binding proteins are phosphorylated in vitro by soluble Ca+2- and phosphatidylserine-dependent protein kinase from mouse brain. 632 76

Nature of cyclic AMP-dependent protein kinases from the uterus of euthyroid and hypothyroid estrus rats was investigated. There was no significant difference between euthyroid and hypothyroid rats in the protein content and the total activity of cyclic AMP-dependent and independent protein kinases of the soluble fractions of uterus tissues. However it was clearly demonstrated that the type I isozyme remarkably decreased in hypothyroid rats in comparison with that of euthyroid rats. The ratio of type I to type II was 1.26 in euthyroid rats and 0.41 in hypothyroid rats. The kinetic properties of the type I and the type II isozymes from both groups of rats showed similar patterns in NaF, Mg2+, cyclic AMP, histone and ATP. It was not observed that the apparent Km values of both the isozymes for histone and ATP were significantly different between euthyroid and hypothyroid rats. Data obtained from these experiments suggested that the thyroid hormone affected the metabolic processes of the uterus through alteration of the isozyme distribution of cyclic AMP-dependent protein kinase.
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PMID:Adenosine 3',5'-monophosphate dependent protein kinase of uterus in euthyroid and hypothyroid rats. 651 98

A protein kinase activity was defined in cytosols and membranes of rat uterus by using two types of enzyme inhibitors. The heat stable protein kinase inhibitor inhibited the cAMP-stimulated protein kinase but not the basal activity measured in the absence of the cyclic nucleotide. However, this basal activity was inhibited by quercetin in a dose-dependent manner, whereas the cAMP-stimulated protein kinase was not inhibited by this bioflavonoid. Thus, quercetin can be used as a tool to define a specific fraction of cAMP-independent protein kinase activity in rat uterine cytosols and membranes. The mature rat uterus is characterized by short (4 days) cyclic changes in tissue growth. Cell proliferation expressed as total uterine DNA content is observed on proestrus, reaches its peak at estrus, and declines sharply during metestrus and diestrus. The quercetin-inhibited protein kinase activity in the membranes of this tissue also changes cyclically and precedes by one phase the cyclic change in tissue proliferation. The clearest effect was seen when the protein substrates for this protein kinase activity were endogenous membrane proteins partially solubilized by Triton X-100 treatment. In contrast no change was observed in cytosolic, quercetin-inhibited protein kinase activity. The cAMP-stimulated protein kinase activity decreased slightly on diestrus. These results support our working hypothesis that tissue proliferation in the uterus and other tissues such as rat mammary gland and mammary tumors, correlates with cAMP-independent, quercetin-inhibited, protein kinase activity in these tissues.
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PMID:Cyclic changes in rat uterine proliferation during the estrous cycle are preceded by changes in protein kinase activity. 654 96

The uterine content of c-fos protein, cyclin B1 (cell cycle protein) and cdc2 p34(cyclin-dependent kinase) in immature and mature rats was determined using the enhanced chemiluminescence(ECL) western blot method. Cyclin B1 was found predominantly in immature rat uterus and cdc2 p34 only in mature rat uterus. Several isoforms of c-fos oncogene protein were present in both mature and immature rat uteri. An additional immunoreactive c-fos protein with an estimated molecular weight of 28 kDa was found in mature rat uterus and was missing in immature uterus. Uteri from ovariectomized rats treated with estrogen and/or ICI 182,780, an antiestrogen, were analyzed by ECL western blot. cdc2 p34 and the c-fos 28 kDa protein were found in estradiol-treated rat uteri and were not detected in uteri of control and ICI 182,780-treated animals; whereas Cyclin B1 was absent in uteri from control and estradiol-treated ovariectomized animals. ICI 182,780 administered to estradiol-treated ovariectomized rats blocked the induction of cdc2 p34 and the c-fos 28 kDa protein in the uterus. The present results show that the production of the cell cycle factors, cyclin B1, cdc2 p34 and c-fos, during rat uterine growth are under different regulatory controls. cdc2 p34 and c-fos 28 kDa protein are under the control of estradiol; whereas cyclin B1 and the majority of the immunoreactive isoforms of c-fos are not influenced by this hormone.
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PMID:Differential effect of estrogen on the production of cyclin B1, cdc2 p34 and c-fos protein in rat uterus. 788 99

Ultraviolet irradiation of human platelet cytosol in the presence of 32P-labelled cyclic GMP (cGMP) can specifically label 110, 80, 55, 49 and 38 kDa proteins; the 110 kDa species is the subunit of cGMP-inhibited phosphodiesterase (PDE III) and the 80 kDa species that of cGMP-dependent protein kinase (Tang et al., 1993, Biochem. J. 294, 329). We have now shown that although photolabelling of platelet PDE III was inhibited by unlabelled cGMP, 8-bromo-cGMP and cyclic AMP (cAMP), it was not affected by phosphorothioate analogues of these cyclic nucleotides. Specific concentration-dependent inhibitions of the photolabelling of PDE III were observed with the following PDE inhibitors: trequinsin (IC50 = 13 +/- 2 nM), lixazinone (IC50 = 22 +/- 4 nM), milrinone (IC50 = 56 +/- 12 nM), cilostamide (IC50 = 70 +/- 9 nM), siguazodan (IC50 = 117 +/- 29 nM) and 3-isobutyl 1-methylxanthine (IBMX) (IC50 = 3950 +/- 22 nM). Thus, measurements of the inhibitory effects of compounds on the photolabelling of platelet PDE III provide a simple quantitative means of investigating their actions at a molecular level that avoids the need to purify the enzyme. Photolabelling of rat platelet lysate or rat heart homogenate by [32P]cGMP showed that the 110 kDa PDE III present in human material was replaced by a 115 kDa protein, labelling of which was also blocked by PDE III inhibitors. Heart and other rat tissues contained much less of this putative 115 kDa PDE III than rat platelets. In contrast, the 80 kDa protein was labelled much less in platelets than in many other rat tissue homogenates (e.g., heart, aorta, uterus and lung). Thus, comparison of the relative amounts of specific photolabelled proteins in different cells may provide an indication of different patterns of cyclic nucleotide action. We compared the abilities of phosphodiesterase inhibitors to block the photolabelling of PDE III in human platelet cytosol and to increase the iloprost-stimulated accumulation of cAMP in intact platelets. Whereas trequinsin (EC50 = 19 +/- 3 nM), lixazinone (EC50 = 122 +/- 8 nM), milrinone (EC50 = 5320 +/- 970 nM) and siguazodan (EC50 = 18880 +/- 3110 nM) all increased platelet cAMP to the same maximum extent, cilostamide and IBMX increased cAMP further, indicating that they inhibited a PDE isozyme in addition to PDE III.
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PMID:Photoaffinity labelling of cyclic GMP-inhibited phosphodiesterase (PDE III) in human and rat platelets and rat tissues: effects of phosphodiesterase inhibitors. 792 8

Contractile response, membrane activity, and protein kinase A (PKA) activity were measured on the longitudinal muscle taken from the estrogen-treated rat uterus, and the influence of Mn ion on the inhibitory effects caused by db cAMP and forskolin was investigated. Phasic contractions generated in the muscle taken from the middle portion of uterus were depressed to 48 and 83% by 30 microM db cAMP and 0.1 microM forskolin in Mg-free Krebs solution, respectively; phasic contractions were more strongly depressed by the agents in the solution containing 0.2 mM Mn. Action potentials consisted of spike and plateau components, and the duration of the plateau potential was reduced by the application of the agents; membrane activity was more strongly depressed in the presence of 0.2 mM Mn. The contractile depression caused by db cAMP was reduced and by forskolin was enhanced by pretreatment of the tissue with 0.6 mM Mn for 30 min. The PKA activity was increased by 39 and 6% of the control, when 30 microM db cAMP and 0.1 microM forskolin were applied, respectively; the PKA activity in response to db cAMP and forskolin was reduced and enhanced, respectively, when the tissues were pretreated with 0.6 mM Mn. It was proposed that Mn ions permeated into cell interior when the muscle was exposed to 0.6 mM Mn, so that the effects of the agents were differently affected. It was also shown that plateau potential dominated in the muscle taken from the ovarian portion, and the contractile inhibition caused by the agents was far weaker.
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PMID:Influence of Mn ion the action of dibutyryl cyclic AMP and forskolin on contraction, membrane response, and cyclic AMP-dependent protein kinase activity in rat myometrium. 811 57

Human cytotrophoblasts in culture aggregate and fuse to form syncytiotrophoblasts. This process is associated with an increase in epidermal growth factor receptor (EGFR) expression [Alsat et al.: J Cell Physiol 154:122-128, 1993]. Recent studies have demonstrated the presence of parathyroid hormone-related protein (PTHrP) in the human uterus and placenta. This led us to study the effect of PTH (1-34) and PTHrP (1-34) on the expression of EGFR during this differentiation process. Both peptides induced a concentration-dependent increase in EGF binding, with a maximal effect at the physiological concentration of 1 nM. EGFR protein level assessed by cross-linking and immunoblotting and EGFR biological activity assessed by measuring its EGF-induced autophosphorylation were increased 2- and 2.5-fold, respectively, when cells were treated for 24 h with 0.1 microM PTHrP or PTH compared to control cells. This effect was time-dependent with a maximum at 3 h of treatment. This treatment also increased trophoblast cell EGFR mRNA levels, suggesting transcriptional regulation of the EGFR. To ascertain whether activation of protein kinase C (PKC) or protein kinase A (PKA) is involved in this PTH effect, we determined EGFR protein level and EGFR autophosphorylation after exposure of cells to PKA inhibitor and PKC inhibitor, alone or together with the peptide. The presence of a PKC inhibitor blocked a further increase in EGFR number by PTH, while PKA inhibitor had no effect. These results show that PTH and PTHrP increase the synthesis of EGF receptors which are strongly expressed in syncytiotrophoblasts and suggested that these peptides might be involved in human placental development.
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PMID:Increase in epidermal growth factor receptor and its mRNA levels by parathyroid hormone (1-34) and parathyroid hormone-related protein (1-34) during differentiation of human trophoblast cells in culture. 822 81

Two kinds of outward K+ currents were examined in single smooth muscle cells from pregnant rat uterus, using whole-cell voltage clamp. The first and faster component was more sensitive to 4-aminopyridine (4-AP), whereas the second and slower (delayed) component was more sensitive to tetraethylammonium (TEA). A possible third K+ component (Ca activated K+ current) was not recorded as the pipette solution included EGTA. Forskolin inhibited the outward current in a concentration-dependent manner (50% inhibition occurred at about 30 microM); it affected the delayed component rather than the fast component. 8-Bromo-cAMP did not alter the outward current. In addition, inhibitors of protein kinase A and GDP-beta S and GTP-gamma S did not affect the forskolin-induced inhibition. These results indicate that forskolin inhibition of the delayed component of the outward current is independent of cAMP generation in the pregnant rat myometrial cells. Therefore, forskolin seems to directly inhibit specific K+ channels, as was reported for several other cell types.
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PMID:Forskolin inhibition of K+ current in pregnant rat uterine smooth muscle cells. 824 35

In the ventromedial hypothalamus (VMH) of female rats, estrogen induces a protein isoform, HIP-70, whose sequence is identical to a protein reported to be phosphoinositol-specific phospholipase-C-alpha (PLC-alpha). Since previous studies explored induction only at the protein level, we examined both the distribution of HIP-70/PLC-alpha mRNA in various tissues and the effects of estrogen on HIP-70/PLC-alpha mRNA. Using slot blot analysis, we found that HIP-70/PLC-alpha mRNA is most abundant in pituitary, uterus, and VMH of female rats compared with other brain regions and tissues. Since these are target tissues for estrogen action, we examined the effects of estrogen on the abundance of HIP-70/PLC-alpha mRNA in these areas. Levels of HIP-70/PLC-alpha mRNA increased greater than 3-fold in the uterus 18 h after estrogen treatment. HIP-70/PLC-alpha mRNA in the VMH also increased about 35% 3 h after estrogen treatment. In situ hybridization corroborated the induction in the ventrolateral ventromedial hypothalamus. No effect of estrogen was observed on pituitary PLC-alpha mRNA. These results indicate that estrogen does increase HIP-70/PLC-alpha mRNA levels in certain tissues. Since the induction of HIP-70/PLC-alpha mRNA in VMH is relatively modest compared to the much larger induction of the HIP-70 protein isoform, regulation of HIP-70/PLC-alpha may entail both pre- and posttranslational mechanisms. Because members of the PLC family catalyze the hydrolysis of phosphatidyl inositol, potentially activating several secondary mediators (intracellular Ca2+, protein kinase-C, and eicanosoids), this second messenger pathway may mediate some effects of estrogen.
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PMID:Estrogen increases HIP-70/PLC-alpha messenger ribonucleic acid in the rat uterus and hypothalamus. 831 93

Although the uterus is a target tissue for LH and its homologue hCG the second messenger system responding to LH/hCG in myometrial cells is not established. In this study we investigated the involvement of protein kinase A and protein kinase C in the action of hCG on porcine myometrial smooth muscle cells in vitro. Myometrium was obtained from ovariectomized gilts given 2.5 mg oestradiol benzoate plus 50 mg progesterone for five consecutive days. Myometrial cells were cultured for 48 h and different doses of hCG were then added. Increasing doses of hCG stimulated concentration-dependent increases in [3H]inositol phosphates (IPs) accumulation in incubations lasting 24 h. The highest dose of hCG (1000 mU/ml) increased turnover of IPs by 2.4-fold as reflected in elevations in IP1, IP2 and IP3, and similar effects were observed with noradrenaline. The time- and concentration-dependent effects of hCG on IPs accumulation occurred between 16 and 24 h of incubation. Incubation of myocytes with the lowest doses of hCG (0.1 and 1 mU/ml) caused a significant increase in cAMP accumulation but the highest doses (10-1000 mU/ml) had no effect on cAMP concentrations. This is the first demonstration that LH/hCG receptor signalling leads to increased inositol phosphate turnover in myometrial cells as well as cAMP generation and it leads to the conclusion that both protein kinase A and protein kinase C signalling mechanisms are involved in gonadotrophin action in porcine myometrial smooth muscle cells.
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PMID:Phospholipase C and adenylate cyclase signalling systems in the action of hCG on porcine myometrial smooth muscle cells. 856 65


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