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

A regulatory role for adenosine 3',5'-monophosphate (cyclic AMP) in the production of the renal hormone rythropoietin following erythropoietic stimulation with cobaltous chloride hexahydrate is proposed. Studies in rates reveal a temporal relationship between renal cyclic AMP levels and plasma titers of erythropoietin. In addition, cobalt increases the activity of an erythropoietin-generating enzyme (renal erythropoietic factor) with maximal enzyme activity occurring after the rise in cyclic AMP levels but before the increase in erythropoietin titers. This increase in renal cyclic AMP is localized to the renal cortex. Cobalt stimulates renal cortical adenylate cyclase but has no effect on renal cyclic nucleotide phosphodiesterase. The addition of cyclic AMP (3 time 10-6 M) and a partially purified cyclic AMP-dependent protein kinase from rat kidney to an inactive preparation of renal erythropoietic factor increases the ability of renal erythropoietic factor to generate erythropoietin. Data from the polycythemic mouse assay, a bioassay used to quantitate erythropoietic activity of test substances, indicate that dibutyryl cyclic AMP is erythropoietically active with respect to its ability to increase radioactive-labelled iron (59Fe) incorporation into heme of newly formed red blood cells. Theophylline, which by itself is erythropoietically inactive, potentiated the erythropoietic effect of cobalt in polycythemic mice. These results suggest that cyclic AMP plays a significant role in the renal production of erythropoietin following cobalt administration. It is postulated that cobalt stimulates renal cortical adenyoate cyclase, thus increasing renal cyclic AMP levels. Cyclic AMP then activates a protein kinase which subsequently stimulates renal erythropoietic factor to generate erythropoietin. A similar cyclic AMP mechanism may be operative after erythropoietic stimulation by exposure to hypoxia or prostaglandin treatment.
 ...
PMID:The role of renal adenosine 3',5'-monophosphate in the control of erythropoietin production. 16 77

If the degree of substitution of Sepharose 4 B with alpha-alkylamines is varied gels of different hydrophobicity are produced. Proteins can be adsorbed when a critical hydrophobicity (ca. 10-12 alkyl residues/Sepharose sphere) is reached. The enzymes phosphorylase kinase, phosphorylase phosphatase, 3',5'-cAMP dependent protein kinase, glycogen synthetase, and phosphorylase b are successively adsorbed as the hydrophobicity of the Sepharose is increased. The capacity of the gels for these enzymes and protein in general increases exponentially reaches plateau values as a function of the degree of substitution. There is no indication of a restriction of the hydrophobic centers for a given protein. The critical hydrophobicity needed to adsorb proteins can either be otained in the above manner or by elongation of the employed alkylamine at a constant degree of substitution. Additonally, as the hydrophobicity of a gel is increased higher binding forces result and desorption of proteins requires an augmentation of the salt concentration in the elution buffer. Elution of proteins from a hydrophobic matrix can be described in terms of salting-in phenomena since desorption is dependent on the type of salt employed and not on the ionic strength alone. This also rules out ionic interactions as a major factor in adsorption per se. By rationally controlling the hydrophobicity of a Sepharose gel the adsorption and elution of a protein may be thus establised that its purification or elimination can be optimally performed.
 ...
PMID:General aspects of hydrophobic chromatography. Adsorption and elution characteristics of some skeletal muscle enzymes. 16 42

Microtubules prepared from chick brain homogenates by successive cycles of assembly-disassembly were found to contain two high-molecular-weight proteins, designated microtubule-associated protein1 and microtubule-associated protein2. Microtubule-associated protein2 (apparent molecular weight 300,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) was the preferred substrate for an endogenous cyclic AMP-dependent protein kinase which appeared to be an integral component of the microtubules. The initial rate of phosphorylation of microtubule-associated protein2 was enhanced 4- to 6-fold by cyclic AMP, with half-maximal stimulation occurring at 2 times 10-7 M cyclic AMP. Under optimal conditions, a total of 1.0 and 1.9 mol of phosphate was incorporated per mole of microtubule-associated protein2, in the absence and presence of cyclic AMP, respectively. Cyclic AMP also stimulated the phosphorylation of tubulin, but the rate of phosphate incorporation per mol of tubulin was only 0.15% that of microtubule-associated protein2. The data raise the possibility that the cyclic AMP-dependent phosphorylation of microtubule-associated protein 2 may play a role in microtubule assembly or function.
 ...
PMID:Cyclic AMP-dependent endogenous phosphorylation of a microtubule-associated protein. 16 13

PGE1, like TSH, can increase cAMP-dependent protein kinase activity in calf thyroid slices. The intracellular levels of cAMP produced by either of these agents alone appeared to correlate well with the degree of kinase activation. PG synthesis did not appear to be necessary for TSH action in this system, since indomethacin, and inhibitor of prostaglandin synthesis, did not alter either cAMP levels or kinase activity in slices incubated with TSH. Both the cAMP level and kinase activity rose when a submaximally effective dose of TSH was added to a maximal dose of PGE1. However, neither the cAMP levels nor the kinase activity produced by a maximal dose of TSH was affected by the addition of PGE1.
 ...
PMID:Effect of PGE1 and TSH on cAMP-dependent protein kinase activity in the thyroid. 16 39

Non-histone chromosomal proteins are phosphorylated and dephosphorylated within the intact nucleus by two independent sets of reactions, a protein kinase reaction which transfers the terminal phosphate group of a variety of nucleoside and deoxynucleoside triphosphates to serine and threonine residues in the proteins, and a phosphatase reaction which cleaves these phosphoserine and phosphothreonine bonds and releases inorganic phosphate. Several lines of evidence are consistent with the hypothesis that the phosphorylation and dephosphorylation of these proteins is involved in gene control mechanisms, including the findings that phosphorylated non-histone proteins are highly heterogeneous and their phosphorylation patterns are tissue specific, changes in their phosphorylation correlate with changes in chromatin structure and gene acticity, addition of phosphorylated non-histone proteins increases RNA synthesis in vitro. and phosphorylated non-histone proteins bind specifically to DNA. Cyclic AMP has both stimulatory and inhibitory properties on non-histone protein phosphorylation, depending on the enzyme fraction and substrate employed A specific protein component whose phosphorylation is inhibited by cyclic AMP has been found to be associated with RNA polymerase. The cyclic AMP-induced decrease in the phosphorylation of this protein correlates with an enhancement of RNA synthesis in vitro. These results suggest that both phosphorylation and dephosphorylation of chromatin-associated proteins may be involved in the control of gene readout.
 ...
PMID:Phosphorylation of non-histone proteins in the regulation of chromosome structure and function. 16 80

Differences exist in the rates at which hormones are inactivated by, or dissociate from, their target tissues. The present studies examined the binding of biologically active TSH to thyroid slices and compared its characteristics to those of PGE. Canine thyroid slices were initally incubated with 5 mU/ML OF BOVINE TSH (TSH-Inital) for 15 min, washed and incubated in media free of hormone for 3 hr. At the conclusion of this second incubation period all slices were again washed. Some were then transferred to media containing 10-2M theophylline for a final 10 min incubation and subsequent measurement of cAMP and protein kinase, while others were transferred to media containing (l-14C)glucose without theophylline for a final 45 min incubation to assess glucose oxidation. Identically treated slices never exposed to TSH served as controls, while others were exposed to TSH only during the final 10 or 45 min incubation periods (TSH-Final). cAMP content determined after significantly increased in TSH-Initial (mean 2.98 plus or minus 0.36 (se) pmol/mg wet wt) compared to control (0.35 plus or minus 0.04), but was less than that in TSH-Final (5.76 plus or minus 0.51). This phenomenon was not unique to canine thyroid, since comparable results were noted in studies of human, bovine or porcine thyroid slices. The protein kinase activity ratio (-cAMP/+cAMP) and glucose oxidation of TSH-Initial were also significantly increased above control following the final 10 min or 45 min incubations respectively. Addition of trypsin to the 3 h incubation abolished the subsequent increase in cAMP in TSH-Initial, while addition of TSH antiserum appreciably reduced this increase. These results are consistent with the persistent binding of biologically active TSH to thyroid. By contrast, evidence of similar persistent binding of PGE1 to thyroid, glucagon to liver, or parathyroid hormone to renal cortex was lacking when assessed by an identical experimental procedure. Differences between the duration of interaction of TSH and PGE1 with thyroid may be dependent or a more gradual dissociation to tissue bound TSH, a more rapid inactivation of bound-PGE1, or both.
 ...
PMID:Evidence for persistent binding of biologically active thyrotropin to thyroid in vitro. 16 69

Plasma membranes have been prepared from porcine thyroid glands using sucrose gradients. The fractions having a density in sucrose of 1.18 g/ml mainly contained plasma membranes and were moderately contaminated with other subcellular components as shown by marker enzyme data. Purified plasma membranes incubated in the presence of [32-P]gamma ATP incorporated 32-P. Kinetics of incorporation of 32-P into endogenous substrates studied in various buffers and with increasing ATP concentration suggest a phosphodephosphorylating system related to cAMP-dependent protein kinase and phosphoprotein phosphatase activities. The two enzymatic activities associated with plasma membranes have been demonstrated using exogenous substrates. cAMP increases and fluoride ions decrease the extent of membrane phosphorylation. The specific activity of protein kinase was 10-12 times higher than in the initial homogenate and was only slightly enhanced in the presence of 0.5% Nonidet as compared to microsomal fraction. cAMP binding to membrane proteins was 3 times higher than to the other particulate fractions. TSH present in the incubating medium or added after 5 min of 32-P labelling induced a rapid stimulation of endogenous phosphorylation followed by a rapid decrease. Phosphorylated membrane substrates were analyzed: high voltage paper electrophoresis after partial hydrolysis indicated that [32-P]phosphate is incorporated into serine and threonine residues as o-phosphate derivatives. SDS-polyacrylamide gel electrophoresis showed several 32--labelled fractions. When enhanced by cAMP, no specific phosphorylation of protein components was observed.
 ...
PMID:Phosphorylation of purified thyroid plasma membranes incubated with [32-P]ATP. 16 13

Preincubation of isolated epididymal fat cells with dexamethasone or treating rats with cortisol enhances the epinephrine-stimulated lipolysis of the cells as well as cAMP-dependent protein kinase activity in homogenates of these fat cell suspensions. During maximal inhibition of phosphodiesterase activity by theophylline or dibutyryl cAMP, this potentiating effect of glucocorticoids on the fat cells was also present. There was no lowering of the total phosphodiesterase activity in homogenates of fat cell suspensions of rats that were treated with cortisol, but there appeared to be a lower activity of the low KM phosphodiesterase activity. It is concluded that induction of protein kinase by glucocorticoid hormone is responsible for its special type of stimulative action on lipolysis.
 ...
PMID:The mechanism of the potentiating effect of glucocorticoids on catecholamine-induced lipolysis. 16 65

Rat hearts were perfused with epinephrine and/or 1-methyl-3-isobutylxanthine for 2 min. These agents raised the concentration of cAMP and increased the fraction of cAMP-dependent protein kinase (EC 2.7.1.70) in the active form. However, the content of cAMP-dependent protein kinase in the soluble fraction of homogenates of these hearts was reduced and the amount in the particulate fraction was increased. A similar redistribution was obtained by adding cAMP to homogenates of control hearts. The reduction in soluble protein kinase content was due to apparent binding of the free catalytic subunit of the enzyme to particulate material (12,000 times g pellet) in media of low ionic strength (smaller than 100 mM KCl). The amount bound was, therefore, proportional to the dissociation of the holoenzyme. The binding was not altered by prior boiling or trypsin treatment of the particulate material, but it was prevented or reversed by the addition of 150 mM KCl. The catalytic subunit of the protein kinase from heart also bound to particulate fractions from liver or Escherichia coli and to various denatured proteins. These findings suggest that the protein kinase activity of membranes and particulate fractions has frequently been overestimated, since isolation of particulate materials has usually been carried out at low ionic strength. The data also imply that intracellular translocation of the protein kinase catalytic subunit, at least in heart tissue, is of questionable physiological significance.
 ...
PMID:On the question of translocation of heart cAMP-dependent protein kinase. 16 13

A number of properties of homogeneous cyclic 3',5'-AMP (cAMP)-dependent protein kinase from rabbit skeletal muscle were determined. The enzyme is shown to be a tetramer consisting of one regulatory subunit dimer and two catalytic subunit monomers. Skeletal muscle protein kinase interacts with cAMP and MgATP as illustrated in the following equilibrium expression: R2C2 - (MgATP)2 + 2 cAMP in equilibrium R2 - (cAMP)2 + 2C + 2 MgATP. MgATP is shown to decrease the affinity of the enzyme for cAMP and to be necessary for recombination of the subunits. The concentration of the enzyme in tissue relative to that of cAMP is high enough to influence kinetic parameters of the activation process by cAMP. The cumulative effects of MgATP and high enzyme concentration are to increase the apparent activation constant for cAMP so that in vivo the enzyme would not be highly activated under basal conditions but would be greatly stimulated by increases in cAMP concentration. As a result, it is not necessary to invoke the concept of compartmentalization of cAMP to explain how it could regulate protein kinase activity in vivo. Finally, data are presented which indicate that a possible function of the heat-stable protein inhibitor of cAMP-dependent protein kinases may be to suppress the activity of protein kinase due to basal concentrations of cAMP. As such, the inhibitor could indirectly change the amount of cAMP needed to allow expression of protein kinase activity.
 ...
PMID:Mechanisms of control for cAMP-dependent protein kinase from skeletal muscle. 16 68


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