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)

Previous studies with isolated adrenocortical carcinoma 494 cells from this laboratory have indicated that the lack of cyclic adenosine 3':5'-monophosphate (cyclic AMP) control in steroidogenesis in the tumor may be due to the defective cyclic AMP-dependent protein kinase enzyme system. This paper describes the partial purification of such an enzyme. Purification was achieved by precipitation of the tumor homogenate with 30 and 45% ammonium sulfate, adsorption on 3% calcium phosphate gel, and chromatography on DEAE-cellulose. Four major protein peaks were isolated. Peak 2 showed cyclic AMP-binding activity and was investigated further for its kinetic properties. In contrast to the cyclic AMP-dependent protein kinase enzyme found in the normal adrenal gland, the enzyme specifically bound cyclic AMP but failed to phosphorylate exogenous histone. It is postulated that lack of the cyclic nucleotide-dependent kinase activity of the protein kinase enzyme may be responsible for the loss of cyclic AMP-regulated corticosterone synthesis in adrenocortical carcinoma cell. It is further shown that the tumor cyclic AMP-binding enzyme undergoes endogenous phosphorylation, which indicates that it has kinase activity but it is independent of cyclic AMP.
...
PMID:Partial purification and characterization of the defective cyclic adenosine 3':5'-monophosphate binding protein kinase from adrenocortical carcinoma. 19 24

The effects of perfusate epinephrine, 1-methyl-3-isobutylxanthine, calcium, and filling pressure were investigated in the perfused working rat heart. Epinephrine produced a rapid increase in cAMP, in the protein kinase activity ratio, and in active phosphorylase. These effects preceded the increase in contractile force produced by the hormone. There was good correlation between protein kinase activation and the increase in force. Epinephrine and the phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine were synergistic in their stimulatory effects on cAMP, protein kinase activity, active phosphorylase, and contractile force. When an increase in the force of contraction was produced either by increasing the filling pressure of the heart or by increasing the perfusate Ca2+ concentration, there was no change in either cAMP levels or protein kinase activity. These data suggest that the effect of beta-adrenergic catecholamines on contractile force is due, at least in part, to cAMP-dependent protein kinase activation. The increase in contractile force produced either by increasing the filling pressure (Frank-Starling phenomenon) or by increasing the perfusate Ca2+ concentration is apparently not mediated by cAMP or the protein kinase.
...
PMID:Involvement of cAMP-dependent protein kinase in the regulation of heart contractile force. 19 11

cGMP-dependent protein kinase from bovine lung has been purified to homogeneity using 8-(2-aminoethyl)-amino adenosine 3':5'-monophosphate/Sepharose. Conditions for adsorption of holoenzyme to the affinity chromatography media followed by competitive ligand elution with cGMP have been determined. The holoenzyme of 150,000 molecular weight is composed of two 74,000 molecular weight subunits which are linked in part by disulfide bridges. Two moles of cGMP are bound per mol of holoenzyme compatible with 1 mol of cGMP/monomer. Dissociation of subunits does not occur upon cGMP binding and protein kinase activation. cGMP-dependent protein kinase has an isoelectric point of 5.4 and a Stokes radius of 50 A. The enzyme is asymmetric with an f/f0 of 1.42 and an axial ratio of 7.4. Determination of enzyme activity at varying concentrations of ATP revealed that cGMP increased the Vmax for ATP without significant effect on the Km. The purified enzyme was maximally active at 5 mM Mg2+; other divalent cations could not substitute for Mg2+. In the presence of Mg2+, strong inhibitory effects of other cations were observed with Mn2+, greater than Zn2+, greater than Co2+ greater than Ca2+. Although maximal cGMP-dependence was observed at pH 5.7 to 7.0, basal activity rose at higher pH values to approach activity observed with cGMP. A molecular model comparing cGMP-dependent protein kinase with cAMP-dependnet protein kinase is presented.
...
PMID:Guanosine 3':5'-monophosphate-dependent protein kinase from bovine lung. Subunit structure and characterization of the purified enzyme. 19 91

Enhancement of calcium uptake into rabbit aortic microsomes was seen at a cyclic AMP concentration of 10(-6) M in the presence of cyclic AMP-dependent protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37). Protein kinase alone also increased calcium uptake, but cyclic AMP alone was without effect. The results suggest that stimulation of calcium sequestration may be the mechanism of cyclic AMP involvement in vascular smooth muscle relaxation.
...
PMID:Stimulation of calcium uptake into aortic microsomes by cyclic AMP and cyclic AMP-dependent protein kinase. 19 33

1. Calcium transport into microsomal vesicles of respiratory (tracheal) smooth muscle was characterized. This calcium transport was ATP dependent and stimulated by the presence of the oxalate ion. The magnitude of transport was similar to that reported for microsomes from other types of smooth muscle. 2. Bovine and rabbit, heavy and light microsomes were isolated from respiratory (tracheal) and vascular (aortic) smooth muscle. Preincubation of these vesicles with cyclic AMP and protein kinase did not alter the transport of calcium into the vesicles. There uas no evidence of phosphate incorporation into microsomal membrane proteins. Similar results were obtained if phosphorylase b kinase replaced the combination of cyclic AMP and protein kinase during the preincubation. 3. The phosphoprotein phosphatase activity of cardiac sarcoplasmic reticulum and smooth muscle microsomes was determined. The activity of this enzyme was found to be several-fold less in the cardiac sarcoplasmic reticulum than in various smooth muscle microsome preparations.
...
PMID:Determination of calcium transport and phosphoprotein phosphatase activity in microsomes from respiratory and vascular smooth muscle. 20 Dec 93

Using a quench-flow technique, the initial velocity of Ca2+ accumulation by isolated cardiac sarcoplasmic reticulum was estimated at free Ca2+ ion concentrations in the range encountered in the myoplasm during the cardiac contraction cycle. With cardiac microsomes exhibiting a Ca2+ accumulative capacity of 25.6 nmol Ca2+/mg protein, initial rates were found to increase from 3.7 to 33.4 nmol Ca2+/mg protein/sec, when the free Ca2+ ion concentration was raised from 0.2 to 18.0 muM. Preincubation of the cardiac microsomes with a party purified soluble cardiac protein kinase, MgATP, and cAMP led to a significant increase in the initial Ca2+ accumulation rate.
...
PMID:Quench-flow measurements of initial rates of Ca2+ accumulation by isolated cardiac sarcoplasmic reticulum. 20 81

Properties of the ATP-dependent calcium transport system of heart sarcolemma are presented. Calcium accumulation (with oxalate) in sarcolemma was increased due to cAMP-dependent protein kinase and phosphorylase b kinase. Protein kinase increased the Vmax of the sarcolemmal calcium accumulation without any detectable effect on the affinity for Ca2+. Both kinases failed to stimulate calcium binding. Protein kinase catalyzed phosphorylation of membrane proteins of molecular weights of 100,000, 25,000, and 14,000. Phosphorylase b kinase also catalyzed phosphorylation of these proteins. Protein kinase stimulated ATPase activity of sarcolemma. Sarcolemma contained endogenous protein kinase and protein phosphatase activities.
...
PMID:Characteristics of heart sarcolemmal calcium transport system and effect of protein kinase on sarcolemmal calcium accumulation. 20 83

The heat-stable protein (protein kinase modulator), partially purified from fresh bovine heart, possessed the ability to inhibit and stimulate adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase and guanosine 3':5'-monophosphate (cGMP)-dependent protein kinase activities, respectively. The inhibitory activity of protein kinase modulator on cAMP-dependent protein kinase was abolished almost completely by trypsin treatment, while the ability to stimulate cGMP-dependent protein kinase activity was resistant to trypsin. Fractionation by a linear potassium phosphate gradient on DEAE-cellulose column did not clearly separate both activities. Phosphorylation of cardiac microsomal component, "phospholamban" (molecular weight = 22,000), was inhibited almost completely by the saturating amounts of protein kinase modulator. This inhibition of phospholamban phosphorylation by protein kinase modulator was accompanied by a decreased Ca uptake rate that had been stimulated by cAMP-dependent protein kinase. These findings indicate that protein kinase modulator is functional in controlling the cAMP-dependent protein kinase-catalyzed phosphorylation of phospholamban and the rate of calcium transport, lending further support for the previously proposed mechanism, in which phospholamban is assumed to serve as a regulator of calcium transport in cardiac sarcoplasmic reticulum.
...
PMID:Effect of protein kinase modulator on cAMP-dependent protein kinase-catalyzed phosphorylation of phospholamban and stimulation of calcium transport in cardiac sarcoplasmic reticulum. 20 86

Similar time courses were obtained for decreases in the rate of calcium transport by cardiac sarcoplasmic reticulum vesicles previously phosphorylated by cAMP-dependent protein kinase and dephosphorylation of the 22,000-dalton phosphoprotein in these membranes. Dephosphorylation of the 22,000-dalton phosphoprotein can be attributed to a phosphoprotein phosphatase in the sarcoplasmic reticular membranes. This membrane-bound phosphoprotein phosphatase may play a role in the reversal of the relaxation-promoting effect of catecholamines on the heart.
...
PMID:Phosphoprotein phosphatase-catalyzed dephosphorylation of the 22,000-dalton phosphoprotein of cardiac sarcoplasmic reticulum. 20 87

A human skeletal actin.tropomyosin.troponin complex was phosphorylated in the presence of [gamma-32 P]ATP, Mg2+, adenosine 3':5'-monophosphate (cyclic AMP) and cyclic AMP-dependent protein kinase (protein kinase). Phosphorylation was not observed when the actin complex was incubated in the absence of protein kinase or 1 microM cyclic AMP. In the presence of 10(-7) M Ca2+ and protein kinase 0.1 mole of [32P]phosphate per 196 000 g of protein was incorporated. This was two-fold higher than the [32P]phosphate content of a rabbit skeletal actin complex but two-fold lower than that of a bovine cardiac actin complex. At high Ca2+, 5.10(-5) M, little change in the phosphorylation of a human skeletal actin complex occurred. Phosphoserine and phosphothreonine were identified in the [32P]phosphorylated actin complex. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate showed that 60% of the label was associated with the tropomyosin binding component of troponin. The inhibitory component of troponin contained 16% of the bound [32P]phosphate. Increasing the Ca2+ concentration did not significantly decrease the [32P]phosphate content of the phosphorylated proteins in the actin complex. No change in the distribution of phosphoserine or phosphothreonine was observed. Half maximal calcium activation of the ATPase activity of reconstitute human skeletal actomyosin made with the [32P] phosphorylated human skeletal actin complex was the same as a reconstituted actomyosin made with an actin complex incubated in the absence of protein kinase at low or high Ca2+.
...
PMID:Phosphorylation of an actin.tropomyosin.troponin complex from human skeletal muscle. 20 9


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

---