Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously demonstrated that growth hormone (GH) promotes an increase in tyrosine kinase activity associated with the GH receptor. To gain insight into the role of GH-dependent tyrosine kinase activity in signaling by GH, we investigated the possibility that GH might stimulate MAP kinase, a serine/threonine/tyrosine kinase thought to be a common element in tyrosine kinase-initiated response cascades. Treatment of 3T3-F442A fibroblasts with 100 ng/ml GH results in a 3-6-fold increase in the ability of cell-free extracts to phosphorylate MAP-2 and myelin basic protein. GH-stimulated kinase activity is unaffected by heparin, H7, or cAMP-dependent protein kinase inhibitor peptide, partially reduced by staurosporin and inhibited by fluoride and calcium ions, indicating that the kinase is not protein kinase C or A, casein kinase, or a calcium/calmodulin-dependent protein kinase. Based on gel permeation chromatography, the molecular mass of the GH-stimulated MAP kinase is approximately kDa. Furthermore, anti-phosphotyrosine antibodies revealed the GH-dependent appearance of two phosphotyrosine-containing proteins in cell-free lysates of GH-treated cells that co-migrate with proteins recognized by anti-MAP kinase antibodies. The GH-dependent increase in MAP kinase activity displays a biphasic time course and is dependent on the concentration of GH applied to the cells. GH-dependent MAP kinase activity, partially purified by Mono-Q chromatography, is inactivated by treatment with alkaline phosphatase. Addition of H7 to the cells prior to the addition of GH has no effect, whereas addition of H8 increases MAP kinase activity in control cells with no effect in GH-treated cells, indicating that protein kinase C is unlikely to be an intermediary in the GH-dependent stimulation of MAP kinase activity. These findings indicate that signaling by GH in 3T3-F443A cells may, at least in part, utilize a kinase cascade similar to those that have been proposed for other membrane receptors with associated tyrosine kinase activity.
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PMID:Stimulation by growth hormone of MAP kinase activity in 3T3-F442A fibroblasts. 131 28

Chicken cardiac C-protein was readily phosphorylated by purified calcium/calmodulin-dependent protein kinase II (CaM-kinase II). Maximum incorporation was about 4 mol of 32P/mol of C-protein subunit. Peptide mapping indicated that some of the sites phosphorylated by CaM-kinase II were located on the same phosphopeptides obtained when C-protein was phosphorylated by the cAMP-dependent protein kinase (peptides T1, T2, and T3). There was a fourth peptide (T3a) which was unique to CaM-kinase II phosphorylation. 32P-Amino acid analysis showed that essentially all of the 32P of peptides T1, T2, and T3a was in phosphoserine. cAMP-dependent protein kinase incorporated 32P only into threonine of peptide T3. Threonine was the preferred site of phosphorylation by CaM-kinase II, but there was significant phosphorylation of a serine in peptide T3. Partially purified C-protein preparations contained an associated calcium/calmodulin-dependent protein kinase. Peptide maps obtained from C-protein phosphorylated by the endogenous kinase were similar to those obtained from C-protein phosphorylated by CaM-kinase II. However, the ratio of phosphothreonine to phosphoserine in peptide T3 was lower. This was due to a contaminating phosphatase in the partially purified C-protein which preferentially dephosphorylated the phosphothreonine of peptide T3. It is suggested that the calcium/calmodulin-dependent protein kinase associated with C-protein is similar or identical to CaM-kinase II and that CaM-kinase II may play a role in the phosphorylation of C-protein in the heart.
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PMID:Phosphorylation of chicken cardiac C-protein by calcium/calmodulin-dependent protein kinase II. 167 69

Calmodulin-dependent protein kinase IV (CaM-kinase IV), a neuronal calmodulin-dependent multifunctional protein kinase, undergoes autophosphorylation in response to Ca2+ and calmodulin, resulting in activation of the enzyme (Frangakis et al. (1991) J. Biol. Chem. 266, 11309-11316). In contrast, the enzyme was phosphorylated by cAMP-dependent protein kinase, leading to a decrease in the enzyme activity. Thus, the results suggest differential regulation of CaM-kinase IV by two representative second messengers, Ca2+ and cAMP.
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PMID:Phosphorylation and functional modification of calmodulin-dependent protein kinase IV by cAMP-dependent protein kinase. 193 Feb 16

The benzophenanthridine alkaloid chelerythrine is a potent, selective antagonist of the Ca++/phospholopid-dependent protein kinase (Protein kinase C: PKC) from the rat brain. Half-maximal inhibition of the kinase occurs at 0.66 microM. Chelerythrine interacted with the catalytic domain of PKC, was a competitive inhibitor with respect to the phosphate acceptor (histone IIIS) (Ki = 0.7 microM) and a non-competitive inhibitor with respect to ATP. This effect was further evidenced by the fact that chelerythrine inhibited native PKC and its catalytic fragment identically and did not affect [3H]- phorbol 12,13 dibutyrate binding to PKC. Chelerythrine selectively inhibited PKC compared to tyrosine protein kinase, cAMP-dependent protein kinase and calcium/calmodulin-dependent protein kinase. The potent antitumoral activity of celerythrine measured in vitro might be due at least in part to inhibition of PKC and thus suggests that PKC may be a model for rational design of antitumor drugs.
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PMID:Chelerythrine is a potent and specific inhibitor of protein kinase C. 224 23

Binding of [3H]-staurosporine to different protein kinases was time-dependent, reversible and saturable. Scatchard analysis of saturation isotherms indicated one class of binding sites for [3H]-staurosporine with dissociation constants (KD) of 9.6, 2.0, 3.0 and 7.4 nM for protein kinase C, cAMP-dependent protein kinase, tyrosine protein kinase and calcium/calmodulin-dependent protein kinase respectively. [3H]-staurosporine binding was fully displaced by unlabelled staurosporine or the related compound K-252a whereas other protein kinase inhibitors (H-7, H-8 and W-7) did not compete with [3H]-staurosporine. These data confirm that sataurosporine shows no selectivity for different protein kinases and suggest the putative existence of distinct, specific binding sites for [3H]-staurosporine on these enzymes.
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PMID:Characterization of specific binding sites for [3H]-staurosporine on various protein kinases. 239 90

The phosphorylation of DNA topoisomerase II in Drosophila Kc tissue culture cells was characterized by in vivo labeling studies and in vitro studies that examined the modification of exogenous enzyme in total homogenates of these embryonic cells. Several lines of evidence identified casein kinase II as the kinase primarily responsible for phosphorylating DNA topoisomerase II. First, the only amino acyl residue modified in the enzyme was serine. Second, partial proteolytic maps of topoisomerase II which had been labeled with [32P]phosphate by Drosophila cells in vivo, by cell homogenates in vitro, or by purified casein kinase II were indistinguishable from one another. Third, phosphorylation in cell homogenates was inhibited by micrograms/ml concentrations of heparin, micromolar concentrations of nonradioactive GTP, or anti-Drosophila casein kinase II antiserum. Fourth, cell homogenates were able to employ [gamma-32P]GTP as a phosphate donor nearly as well as [gamma-32P]ATP. Although topoisomerase II was phosphorylated in homogenates under conditions that specifically stimulate protein kinase C, calcium/calmodulin-dependent protein kinase, or cAMP-dependent protein kinase, modification was always sensitive to anti-casein kinase II antiserum or heparin. Thus, under a variety of conditions, topoisomerase II appears to be phosphorylated primarily by casein kinase II in the Drosophila embryonic Kc cell system.
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PMID:Phosphorylation of DNA topoisomerase II in vivo and in total homogenates of Drosophila Kc cells. The role of casein kinase II. 284 38

Incubation of rat pheochromocytoma PC12 cells with the calcium ionophore, A23187 (10(-5) M), 56 mM K+, or dibutyryl cAMP (2 mM) is associated with increased activity and enhanced phosphorylation of tyrosine hydroxylase in the cells. Both the activation and the increased phosphorylation of tyrosine hydroxylase produced by A23187 and 56 mM K+ are dependent on the presence of extracellular calcium, whereas similar effects produced by dibutyryl cAMP are independent of calcium. The effects of 56 mM K+ plus dibutyryl cAMP or A23187 plus dibutyryl cAMP on the activation and phosphorylation of tyrosine hydroxylase are additive. In contrast, the effects of 56 mM K+ plus A23187 on either the activation or the phosphorylation of the enzyme are not additive. Following stimulation of intact PC12 cells with 32Pi, in order to label ATP stores, and tryptic digestion of the phosphorylated enzyme, separation of the tryptic phosphopeptides by high pressure liquid chromatography yields four distinct 32P-peptide peaks. Incubation of the cells in the presence of either 56 mM K+ or A23187 is associated with increased 32Pi incorporation into three peptides whereas, in the presence of dibutyryl cAMP, increased 32Pi incorporation is observed in only one of these peptides. When tyrosine hydroxylase purified from rat pheochromocytoma tumor is incubated in vitro with [gamma-32P]ATP and either cAMP-dependent or calcium/calmodulin-dependent protein kinase under appropriate conditions, increased phosphorylation of tyrosine hydroxylase is observed. However, even though in vitro phosphorylation by cAMP-dependent protein kinase is associated with activation of tyrosine hydroxylase, in vitro phosphorylation by calcium/calmodulin-dependent protein kinase does not lead to activation of the enzyme. Tryptic digestion of tyrosine hydroxylase phosphorylated by calcium/calmodulin-dependent protein kinase yields three distinct 32P-peptide peaks, which are identical to those phosphorylated by treatment of intact PC12 cells with either high K+ or A23187. In contrast, cAMP-dependent protein kinase phosphorylates only one peptide, which is identical to that phosphorylated by treatment of the intact cells with dibutyryl cAMP. These results indicate that tyrosine hydroxylase is activated and phosphorylated at multiple sites in PC12 cells exposed to 56 mM K+ or A23187. The results suggests that the in situ phosphorylation of these sites is catalyzed by calcium/calmodulin-dependent protein kinase; however, phosphorylation by this protein kinase is not sufficient to activate the enzyme.
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PMID:Phosphorylation of tyrosine hydroxylase on at least three sites in rat pheochromocytoma PC12 cells treated with 56 mM K+: determination of the sites on tyrosine hydroxylase phosphorylated by cyclic AMP-dependent and calcium/calmodulin-dependent protein kinases. 287 91

Chromaffin cells were isolated from bovine adrenal medullae and maintained in primary culture. After prelabeling with 32PO4, exposure of the chromaffin cells to acetylcholine increased the phosphorylation of a Mr approximately equal to 100,000 protein and a Mr approximately equal to 60,000 protein (tyrosine hydroxylase), visualized after separation of total cellular proteins in naDodSO4/polyacrylamide gels. Immunoprecipitation with antibodies to three known phosphoproteins ("100-kDa," "87-kDa," and protein III) revealed an acetylcholine-dependent phosphorylation of these proteins. These three proteins were also shown to be present in bovine adrenal chromaffin cells by immunolabeling techniques. "100-kDa" is a Mr approximately equal to 100,000 protein selectively phosphorylated by calcium/calmodulin-dependent protein kinase III, "87-kDa" is a Mr approximately equal to 87,000 protein selectively phosphorylated by protein kinase C, and protein III is a phosphoprotein doublet of Mr approximately equal to 74,000 (IIIa) and Mr approximately equal to 55,000 (IIIb) phosphorylated by cAMP-dependent protein kinase and calcium/calmodulin-dependent protein kinase I. Furthermore, 100-kDa was shown to be identical to the Mr approximately equal to 100,000 protein whose phosphorylation was increased by acetylcholine treatment. The acetylcholine-dependent increase in phosphorylation of tyrosine hydroxylase, 100-kDa, 87-kDa, and protein III required extracellular calcium and was mimicked by nicotine, veratridine, elevated K+, and calcium ionophore A23187, but not by muscarine. In addition, forskolin increased the phosphorylation of tyrosine hydroxylase, 100-kDa, and protein III, but not that of 87-kDa. Phorbol 12,13-dibutyrate increased the phosphorylation of tyrosine hydroxylase, 87-kDa, and protein III, but not that of 100-kDa. The data demonstrate that cholinergic activation of chromaffin cells increases the phosphorylation of several proteins and that several protein kinase systems may be involved in these effects.
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PMID:Cholinergic regulation of protein phosphorylation in bovine adrenal chromaffin cells. 289 32

Postsynaptic membranes, rich in the nicotinic acetylcholine receptor, were isolated from the electric organ of Torpedo californica and shown to contain a cAMP-dependent protein kinase and a calcium/calmodulin-dependent protein kinase. The cAMP-dependent protein kinase phosphorylated the gamma and delta subunits of the acetylcholine receptor. The phosphorylated subunits were identified after purification of the acetylcholine receptor by affinity chromatography on a choline carboxymethyl affinity gel. In contrast, the calcium/calmodulin-dependent protein kinase phosphorylated proteins that were separated from the acetylcholine receptor by affinity chromatography. Protein kinase inhibitor, a specific inhibitor of the catalytic subunit of cAMP-dependent protein kinase, abolished the basal endogenous phosphorylation of the gamma and delta subunits of the receptor. cAMP activation of the endogenous phosphorylation of the gamma and delta subunits was dose dependent with a half-maximal response at 25 nM. Studies were also carried out with acetylcholine receptor purified from T. californica and catalytic subunit of cAMP-dependent protein kinase purified from bovine heart. The purified acetylcholine receptor was rapidly and specifically phosphorylated on the gamma and delta subunits by the purified catalytic subunit of cAMP-dependent protein kinase to a stoichiometry of 1.0 and 0.89 mol of (32)P per mol of receptor, respectively. The initial rates of phosphorylation of the gamma and delta subunits of the receptor were comparable to those of histone f2B and synapsin I (protein I), two of the most effective substrates for the catalytic subunit. Under the conditions used, the gamma and delta subunits had K(m) values of 4.0 and 3.3 muM and V(max) values of 2.7 and 2.1 mumol/min per mg, respectively. The results are consistent with the idea that the acetylcholine receptor is phosphorylated in vivo by a cAMP-dependent protein kinase.
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PMID:cAMP-dependent protein kinase phosphorylates the nicotinic acetylcholine receptor. 630 72

Regulation of calcium transport by sarcoplasmic reticulum provides increased cardiac contractility in response to beta-adrenergic stimulation. This is due to phosphorylation of phospholamban by cAMP-dependent protein kinase or by calcium/calmodulin-dependent protein kinase, which activates the calcium pump (Ca2+-ATPase). Recently, direct phosphorylation of Ca2+-ATPase by calcium/calmodulin-dependent protein kinase has been proposed to provide additional regulation. To investigate these effects in detail, we have purified Ca2+-ATPase from cardiac sarcoplasmic reticulum using affinity chromatography and reconstituted it with purified, recombinant phospholamban. The resulting proteoliposomes had high rates of calcium transport, which was tightly coupled to ATP hydrolysis (approximately 1.7 calcium ions transported per ATP molecule hydrolyzed). Co-reconstitution with phospholamban suppressed both calcium uptake and ATPase activities by approximately 50%, and this suppression was fully relieved by a phospholamban monoclonal antibody or by phosphorylation either with cAMP-dependent protein kinase or with calcium/calmodulin-dependent protein kinase. These effects were consistent with a change in the apparent calcium affinity of Ca2+-ATPase and not with a change in Vmax. Neither the purified, reconstituted cardiac Ca2+-ATPase nor the Ca2+-ATPase in longitudinal cardiac sarcoplasmic reticulum vesicles was a substrate for calcium/calmodulin-dependent protein kinase, and accordingly, we found no effect of calcium/calmodulin-dependent protein kinase phosphorylation on Vmax for calcium transport.
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PMID:Purified, reconstituted cardiac Ca2+-ATPase is regulated by phospholamban but not by direct phosphorylation with Ca2+/calmodulin-dependent protein kinase. 866 79


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