Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of the human rIL-1 alpha and rTNF-alpha on the binding of 125I-labeled epidermal growth factor ([125I]EGF) to its receptor (EGF-R) has been studied in human gingival fibroblasts (HuGi). Incubation of these cells with recombinant cytokines at 37 degrees C caused a rapid, dose-dependent decrease in their ability to subsequently bind subsaturating levels of [125I]EGF at 4 degrees C. Inhibition was evident at 5 min after addition of cytokines, reached a maximal level (60-70% reduction) after 15 to 30 min, and declined thereafter. Normal EGF binding was attained by 2 h. Half-maximal inhibition of EGF binding occurred at 10 pM IL-1 and 50 pM TNF. The two cytokines were not additive in their effect. Competition experiments at 4 degrees C showed that the cytokines did not interact directly with EGF-R; Scatchard analysis of binding of [125I]EGF to HuGi after treatment with IL-1 and TNF revealed an increase in EGF-R Kd from 0.75 nM to 2.9 nM with no change in receptor number. The effect of IL-1 and TNF on EGF-R was compared with that of the tumor-promotor PMA which is known to "transmodulate" EGF-R affinity by activating protein kinase C which then phosphorylates EGF-R. PMA caused a greater inhibition of EGF binding to HuGi (80 to 85% inhibition; ED50 = 500 pM), and recovery of binding was much slower. Importantly, in HuGi made deficient in protein kinase C by prolonged incubation with PMA, addition of fresh PMA no longer affected EGF binding, while the response to IL-1 and TNF was intact. Cytokine- but not PMA-mediated EGF-R transmodulation was partially reversed by treatment of the cells with millimolar concentrations of the kinase inhibitor amiloride. HuGi were incubated with H3 32PO4, stimulated with PMA or cytokines, and EGF-R were immunoprecipitated; IL-1 and TNF, like PMA, caused a 2- to 5-fold increase in receptor phosphorylation. We conclude that occupation of IL-1 and TNF-R activates a protein kinase, distinct from kinase C, for which EGF-R is a substrate.
...
PMID:IL-1 and TNF transmodulate epidermal growth factor receptors by a protein kinase C-independent mechanism. 278 20

The binding of epidermal growth factor (EGF) to its plasma membrane receptor results in the stimulation of a tyrosyl residue-specific protein kinase, which has been shown to be part of the receptor. The mechanism by which EGF binding give rise to the stimulation of kinase activity is not understood in detail; however, a number of recent studies have implicated receptor dimerization or oligomerization in this process. We prepared Triton X-100 extracts of A431 cells in which the concentration of EGF receptors was on the order of 10(-7) M. When samples of the extracts were incubated with or without EGF and then treated with the high-yield cross-linking reagent bis(sulfosuccinimidyl)suberate (BS3), covalent receptor dimers could be detected in high yield in samples that had been treated with both EGF and BS3, whereas only monomeric receptor was detected in untreated samples or in samples that had been treated with either EGF or BS3. The yield of receptor dimers trapped by cross-linking correlated with the stimulation of autophosphorylation by EGF and with the concentration of EGF present. EGF-induced receptor dimers were also efficiently cross-linked in highly purified receptor preparations, suggesting that EGF-induced dimerization is a process intrinsic to the receptor, requiring no additional accessory proteins.
...
PMID:High-yield trapping of EGF-induced receptor dimers by chemical cross-linking. 278 12

Synthetic peptide substrates specific for cAMP-dependent protein kinase, protein kinase C, ribosomal S6 kinase, and Ca2+/calmodulin-dependent protein kinases were used to monitor regulation of these protein kinases in digitonin-permeabilized PC12 cells following treatment with nerve growth factor (NGF) and epidermal growth factor (EGF). cAMP-dependent protein kinase was not activated by NGF and EGF. In addition, neither the Ca2+/calmodulin-dependent nor -independent activity of a protein kinase similar to Ca2+/calmodulin kinase II was affected by growth factor treatment. However, protein kinase C was rapidly and transiently activated and ribosomal S6 kinase activity was persistently elevated. Maximal protein kinase C activity was observed after 2 to 5 min of treatment and, subsequently, returned to control levels within 30 to 40 min. In contrast, S6 kinase activity was maximal within 15 min of NGF and EGF addition and was stably maintained for at least 24 hr. In addition to protein kinase C and S6 kinase, NGF and EGF regulated a protein kinase that was maximally elevated after 15 to 30 min and returned to control levels within 3 to 5 hr. This kinase (approximately 100 kDa) failed to bind to a calmodulin affinity column and eluted from a cation exchange column as a single major species that was distinct from S6 kinase activity, which eluted as multiple peaks. The findings indicate that at least three protein kinases are rapidly activated in PC12 cells following treatment with NGF and EGF. The distinct durations of activation of each kinase implicates significantly different roles for each in growth factor signalling in PC12 cells.
...
PMID:Detection of nerve growth factor and epidermal growth factor-regulated protein kinases in PC12 cells with synthetic peptide substrates. 278 35

The activity of a protein kinase specific to ribosomal protein S6 was determined in early loach embryos in basal conditions and after their treatment with epidermal growth factor (EGF). The cytosol of loach blastoderms isolated at the early gastrula stage possessed a high level of protein kinase activity catalysing incorporation of 0. 33 pmol.min-1.mg-1 of Pi into exogenous S6 protein of rat liver ribosomal 40S subunit. The treatment of embryos for 30 min with EGF (10 ng/ml) added to the incubation medium caused an 25% increase of total S6-kinase activity in cytosol compared with its counterpart in non-stimulated embryos. After chromatography of loach embryos cytosol on DE-52 three fractions possessing S6-kinase activity were revealed, which were eluted with 10 microM cAMP (I), 150 mM NaCl (II) and 300 mM NaCl (III), respectively. After treatment of blastoderms with EGF in the described conditions the enzymatic activity 2-fold decreased in fraction I, increased in fraction II 4-fold and remained practically unchanged in fraction III. The mitogen-stimulated kinase, apart from S6 protein, phosphorylated also casein and but not histone H1.
...
PMID:[Epidermal growth factor stimulates protein kinase activity, specific for ribosomal protein S6 in loach embryo blastoderm]. 278 4

Non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) cell lines were studied for epidermal growth factor (EGF) receptor expression. All NSCLC cell lines tested (eight of eight) had specific EGF binding sites, whereas only five of 11 SCLC cell lines bound EGF. NSCLC and SCLC cell lines expressed the same type of high affinity EGF binding sites with a Kd of 0.5 to 4.5 nM; however, NSCLC cells bound significantly more EGF than SCLC cell lines. The amount of binding sites in NSCLC cells ranged between 71 and 1,000 fmol/mg of protein and in SCLC cells, between 26 and 143 fmol/mg of protein. The two SCLC cell lines with EGF binding values within the range of NSCLC belonged to the variant subtype of SCLC. By means of an anti-erbB serum and indirect radioimmunoprecipitation, a strong Mr approximately 170,000 protein band could be detected in the NSCLC cell lines. This protein corresponds to the EGF receptor molecule. Its identity was proven by competition with excess erbB antigen for the antibody during the radioimmunoprecipitation. Furthermore, this Mr 170,000 protein exhibited protein kinase activity as evidenced by in vitro autophosphorylation. The radioactivity incorporated into the Mr 170,000 band in radioimmunoprecipitation and protein kinase assays was 10 to 100 times lower in these SCLC cell lines which were positive in the EGF binding assay compared to the NSCLC cell lines. We conclude that NSCLC in contrast to SCLC expresses high levels of EGF receptors which may be used to facilitate the differential diagnosis in some cases of lung cancer. These data suggest that EGF may play a role in growth and differentiation of NSCLC.
...
PMID:Epidermal growth factor receptor expression in human lung cancer cell lines. 283 15

A brush-border membranal proteinase, which specifically clips the catalytic subunit of cAMP-dependent protein kinase, is shown to cleave the receptor for the epidermal growth factor (EGF) (Mr = 170,000) into two fragments of Mr = 140,000 and 30,000. The 140-kDa fragment retains its EGF-binding site and its EGF-dependent protein tyrosine kinase activity on exogenous substrates, but it loses its capacity to undergo self-phosphorylation. It is shown to be distinct from the 150-kDa fragment of the EGF receptor obtained by the Ca2+-activated neutral proteinase. The membranal proteinase strictly recognizes the native structure of the receptor and fails to cleave either the denatured receptor or its 150-kDa degradation product. Thus the membranal proteinase acts as a conformation-recognizing probe for both the protein-tyrosine kinase domain of the EGF receptor and the catalytic subunit of cAMP-dependent protein-Ser/Thr kinase, suggesting that the known sequence homology between these two kinases is also reflected in their conformation. The well defined 140-kDa fragment described here is useful for structure-function studies of the EGF receptor.
...
PMID:The epidermal growth factor receptor as a substrate for a kinase-splitting membranal proteinase. 283 Feb 86

The epidermal growth factor (EGF) receptor exists in a monomeric (170 kDa) form and in several aggregated states (360 kDa, greater than 500 kDa). The hypothesis that the oligomerization of the receptor is required for the stimulation of the kinase was tested by correlating the oligomeric state of the receptor with the protein kinase activity. EGF and sphingosine stimulate the phosphorylation of an exogenous peptide substrate by the receptor to an equal extent. Chemical cross-linking using disuccinimidyl suberate and the analysis of EGF receptor complexes by Western blotting demonstrated that EGF caused the aggregation of receptors. Similar results were obtained when [32P]phosphate-labeled receptors were cross-linked using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. These results were confirmed by sucrose density gradient sedimentation analysis. In contrast to the effects of EGF, incubation of EGF receptors with sphingosine did not cause the oligomerization of the receptors. These data demonstrate that the EGF receptor kinase can be stimulated independently of the aggregation of the receptors.
...
PMID:Activation of the epidermal growth factor receptor tyrosine protein kinase in the absence of receptor oligomerization. 283 84

Exposure of rats to phenobarbital (PB), a tumor promoter in the two-stage hepatocarcinogenesis model, in their diet (0.06%) induces alterations in insulin receptors in the hepatocytes. There is a decrease both in the number of receptors and the dissociation constant (Kd) when compared with animals fed control laboratory diet. The number of insulin receptors/cell and the Kd were respectively: 183,000 +/- 19,000 and 15.3 +/- 2.5 nM for controls; 47,000 +/- 5000 and 2.8 +/- 0.3 nM for PB. The glycogen synthesis in response to insulin was found to be unresponsive in the hepatocytes from rats exposed to PB. Glucagon receptors on hepatocytes, however, were unaltered in animals treated with PB or fed a choline-deficient (CD) diet and the glucagon-stimulated glycogenolytic responses were also comparable to the controls. There is, therefore, a selective alteration in the hepatocyte surface membrane receptors. Both PB and CD have been shown to reduce the hepatic cell membrane receptors for epidermal growth factor, indicating that the two different tumor promoters alter peptide receptors with endogenous protein kinase activities. This similar though selective effect of the tumor promoters on cell surface receptors may be of significance in their action in carcinogenesis by having an effect on the alteration of regulation of cell growth and metabolism.
...
PMID:Alterations induced by phenobarbital, a liver tumor promoter, in hepatocyte receptors for insulin and glucagon and glycogen metabolism. 283 98

We have prepared site-specific antibodies toward human insulin, insulin-like growth factor-I, and epidermal growth factor receptors with chemically synthesized peptides derived from the cDNA-predicted amino acid sequences of these receptors. Two classes of antibodies were produced toward each receptor: one toward the carboxyl termini and the other against the kinase domains containing sequences homologous to the tyrosyl phosphorylation site of the product of src gene (pp60v-src). Both classes of antibodies specifically immunoprecipitated the appropriate 125I-ligand-receptor complexes and [35S]methionine-labeled receptors with almost equal potencies. Antibodies toward the kinase domains inhibited both autophosphorylation and tyrosine kinase activity of the corresponding receptors in a cell-free system, whereas antibodies toward the carboxyl termini did not. Microinjection of the kinase-inhibitory antibodies into the cytoplasm of human epidermoid carcinoma KB cells blocked the ability of the corresponding ligand to induce membrane ruffling. In contrast, these inhibitory antibodies did not block the ability of noncorresponding ligands to induce the same response. Furthermore, control immunoglobulin and antibodies toward the carboxyl termini did not block this biological response. These results support a role for the tyrosine-specific protein kinase activities of these growth factor receptors in mediating their biological effects and suggest that the regions homologous to the tyrosyl phosphorylation site of pp60v-src are important for these kinase activities both in cell-free and intact cell systems.
...
PMID:Requirement for receptor-intrinsic tyrosine kinase activities during ligand-induced membrane ruffling of KB cells. Essential sites of src-related growth factor receptor kinases. 283 87

Addition of epinephrine to primary cultured adult rat hepatocytes stimulated their DNA synthesis dose-dependently, especially in presence of insulin and epidermal growth factor. This effect of epinephrine was strongly inhibited by an alpha 1-antagonist, prazosin, but not by a beta-antagonist, propranolol, and was also slightly inhibited by an alpha 2-antagonist, yohinbin. These results indicate that the stimulation of DNA synthesis of hepatocytes by epinephrine is mediated predominantly by an alpha 1-action. 12-o-Tetradecanoylphorbol-13-acetate (TPA) or Ca2+-ionophore A-23187 stimulated DNA synthesis of Swiss 3T3 cells, but did not induce DNA synthesis of hepatocytes either singly or in combination. The fact that pretreatment of hepatocytes with TPA caused down-regulation of the stimulatory effect of epinephrine on DNA synthesis of hepatocytes within 15 min suggested that the effect of epinephrine on hepatocytes is mediated by its alpha 1 receptor and that TPA activated protein kinase c in the hepatocytes. Addition of dibutyryl cGMP did not induce DNA synthesis of hepatocytes. Therefore, the alpha 1-action of epinephrine that induce stimulation of DNA synthesis of primary cultured adult rat hepatocytes was apparently not mediated by either activation of phospholipid-dependent protein kinase or Ca2+ mobilization. Possible alternative mechanism was discussed.
...
PMID:Mechanism of stimulation of DNA synthesis induced by epinephrine in primary culture of adult rat hepatocytes. 284 21


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---