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

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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)

A previous study demonstrated that the translational inhibitor from lysates of heme-deficient rabbit reticulocytes is associated with a protein kinase activity. Chromatography of this inhibitor preparation on phosphocellulose yields two distinct protein kinase activities, PC1 and PC2. PC1, which consitutes about 90% of the activity in the unresolved preparation, does not inhibit protein synthesis in lysates, but actively phosporylates calf thymus histone II in a 3':5'-cyclic AMP-denpendent reaction. PC2 contains the translational inhibitor, phosphorylates histone poorly, and is not cyclic AMP-dependent. While [gamma-32P]ATP as the phosphate donor, the two kinase fractions were analyzed with the putative substrates, salt-washed 40S ribosomal subunits, and the initiation factor that mediates the binding of Met-tRNAf to the 40S subunit. PC1 is inactive with the initiation factor, but phosphorylates 40S subunits at a single major site that migrates as a 31,000-dalton band in sodium dodecyl sulfate-acrylamide gels; phosphorylation requires cyclic AMP. Similar phosphorylation of the reticulocyte 40S site (31,000 daltons) can be demonstrated with other cyclic AMP-dependent kinases from reticulocytes, rat liver, and bovine heart muscle. PC2 phosphorylates the small subunit (38,000 daltons) but not the large subunit(s) of the initiation factor; the reaction does not require cyclic AMP. PC2 does not phosphorylate 40S subunits. In the presence of 40S subunits, the initiation factor appears to be rapidly bound in a manner that effectively blocks phosphorylation of the initiation factor by PC2; under the same conditions phosphorylation of the 40S subunit by PC1 is not affected. The initiation factor has been shown to reverse the inhibitions of protein chain initiation induced in lysates by heme deficiency, double-stranded RNA, oxidized glutathione, or the purified translational inhibitor. The observation that the Met-tRNAf binding factor is phosphorylated by PC2 supports the hypothesis that this initiation factor is a target for the action of the translational inhibitor activated in heme deficiency.
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PMID:Regulation of protein synthesis in reticulocyte lysates: phosphorylation of methionyl-tRNAf binding factor by protein kinase activity of translational inhibitor isolated from hemedeficient lysates. 18 60

Choriogonadotropin and lutropin have been found to activate cyclic AMP-dependent protein kinase in ovarian cells isolated by collagenase dispersion from immature rats. The stimulatory effect of gonadotropins was dependent on both hormone concentration and incubation time. Choriogonadotropin at 1 mug/ml fully stimulated the protein kinase activity within 5 min of incubation, and this effect was specific for choriogonadotropin and lutropin-like activity. In addition, protein kinase activity has been characterized with respect to salt sensitivity, cyclic AMP binding, and its responsiveness to gonadotropins and other peptide hormones. Ovarian protein kinase was susceptible to high salt concentrations. The addition of 0.3-1.0 M-NaCl in incubation medium increased the activity ratio with a concomitant decrease in cycle AMP-dependence. The salt effect on protein kinase was observed both from hormone-treated and untreated cells. The hormone-stimulated and unstimulated protein kinase activity was completely stable in the absence of NaCl. No change in the activity ratio was observed when cellular extracts were assayed for protein kinase activity either immediately or after 2 h in the absence of added salt. Gel filtration in the absence of NaCl of cellular extracts prepared from choriogonadotropin-treated and untreated cells showned only a single peak of protein kinase activity that was sensitive to exogenously added cyclic AMP. By contrast, when 0.5 M-NaCl was included in the column buffer, the chromatography of untreated extract showed two peaks of protein kinase activity. The first peak was sensitive to added cyclic AMP, whereas the second peak was insensitive to it. Under identical experimental conditions, protein kinase from gonadotropin-treated cells showed, on gel filtration, only one peak of activity that was totally insensitive to added cyclic AMP. DEAE-cellulose column chromatography of a 20000 g supernatant fraction resulted in a peak of kinase activity that eluted in approx. 0.15 M-NaCl, similar to the similar to the elution of type II protein kinases as described by Corbin et al. (1975) (J. Biol. Chem. 250, 218-225). Choriogonadotropin stimulation produced a decrease in the capacity of protein kinase to bind exogenous cyclic [3H]AMP, with a concomitant increase in the kinase activity ratio. These results are consistent with the notion that cyclic AMP, GENERATED IN SITU Under hormonal stimulation, binds tot he regulatory subunit of protein kinase with subsequent dissociation of the active catalytic subunit from the holoenzyme.
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PMID:Ovarian adenosine 3':5'-cyclic monophosphate-dependent protein kinase(s). Regulation by choriogonadotropin and lutropin in rat ovarian cells. 18 32

Inorganic salts, several proteins and traces of protein precipitants were tested to find out by what mechanisms they modulate the binding of cyclic [3H]AMP to protein kinase (ATP-protein phosphotransferase; EC 2.7.1.37). The separation of free and bound cyclic AMP by (NH4)2SO4 precipitation was unaffected by the above agents and was more reliable than the Millipore filtration technique. Several binding sites for cyclic AMP were revealed in adrenal-cortex extract. When this extract was used as binding reagent in an assay for cyclic AMP, the standard curve was distorted in the presence of KCl because the salt affected the different binding sites to a varying extent. At high ionic strenth the protein kinase isoenzyme I dissociated and showed an extraordinarily high affinity for cyclic AMP. Trichloroacetate and perchlorate at very low concentrations were able to dissociate the protein kinase and modulate its binding characteristics as well. A progressive decrease in the cyclic AMP-binding capacity occurred on prolonged incubations. The binding protein was protected against inactivation by 2-mercaptoethanol, EDTA and several proteins. It was more resistant to denaturation when complexed to cyclic AMP. The enhancement of cyclic AMP binding by bovine serum albumin was investigated in some detail and appeared to be a pure stabilizing effect. It is proposed that the competitive-binding assays for cyclic AMP based on protein kinase be conducted at high ionic strength and in the presence of stabilizers (protein, EDTA, 2-mercaptoethanol). The interference from agents that may dissociate the protein kinase or influence its stability will thus be decreased.
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PMID:Factors affecting the binding of [3H]adenosine 3':5'-cyclic monophosphate to protein kinase from bovine adrenal cortex. 19 3

The species of proteins associated with chromatin and ribosomes of simian virus 40 (SV40)-transformed and untransformed monkey, mouse, and rat cells have been compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after phosphorylation of these proteins either in vivo or in vitro. In vitro phosphorylation was carried out by protein kinase associated with these organelles and [gamma-(32) P]ATP as the phosphoryl donor. The reaction products contained both phosphoserine and phosphothreonine in approximately equal amounts. The electrophoretic analysis of the phosphorylated proteins revealed that the highly phosphorylated protein with a molecular weight of approximately 90,000 (90K protein) was associated with chromatin and ribosomes from transformed cells but not from untransformed cells. The 90K protein could be extracted from chromatin and ribosomes with 0.5 to 1.0 M NaCl or KCl. The 90K protein was still associated with the runoff ribosomes prepared by the puromycin reaction of the post-mitochondrial supernatant in the protein-synthesizing system. In vitro phosphorylation of chromatin and ribosomes from SV40 tsA-transformed mouse and rat cells indicated that the amounts of 90K protein associated with these organelles decreased greatly when the cells were cultivated at the restrictive temperature. A similar temperature-dependent decrease in the amount of (32)P-labeled 90K protein was observed in nonhistone chromosomal and ribosome-associated protein fractions prepared from SV40 tsA-transformed cells labeled with [(3)H]leucine and [(32)P]orthophosphate in vivo. In vitro phosphorylated 90K protein in nonhistone chromosomal and ribosome-associated proteins extracted with high salt was not immunoprecipitated with anti-SV40 T sera.
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PMID:Simian virus 40 gene A regulates the association between a highly phosphorylated protein and chromatin and ribosomes in simian virus 40-transformed cells. 19 84

Protein kinase activity was detected and assayed directly on polyacrylamide gels after disc electrophoresis of the 100,000 X g supernatant fraction of brown adipose tissue of infant rats. Nine major bands of activity were detected, eight of which could be stimulated by cAMP or inhibited by the cAMP-dependent protein kinase inhibitor protein. This electrophoretic technique revealed heterogeneity in the cAMP-dependent protein kinase activity eluted from DEAE-cellulose by high concentrations of salt, but not in the peak of activity eluted by low concentrations of salt. The catalytic properties and substrate specificities of the kinases in the various bands were studied while the enzymes were still in the gels. The activity in each band differed from each of the others in at least one of these properties. The activities of the protein kinases in brown fat changed as the animals grew, and each band exhibited a distinct and unique developmental pattern. The major changes in kinase activities occurred in the immediate post-parturition period, then at 15 days after birth and at weaning. These developmental stages coincide with the periods during which the tissue undergoes changes in the rate of its proliferation, differentiation, and functional activity.
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PMID:Protein kinases in brown adipose tissue of developing rats. Electrophoretic separation and assay of soluble protein kinases on polyacrylamide gels and a study of their properties and changes during development. 19 49

The Sertoli cell of the rat testis contains two cytoplasmic forms of adenosine 3',5' monophosphate (cyclic AMP)-dependent protein kinase, designated as Peak I and Peak II, which change in relative proportion during Sertoli cell maturation. Peak I and Peak II differ in their subunit interaction. Thus, while the substrates, ATP and histone, affect cyclic AMP binding to Peak I, neither of these compounds affect the binding of cyclic AMP to the Peak II enzyme. The effects of cyclic AMP binding to Peak I appear to be due to the fact that histone and high ionic strength cause dissociation of the Peak I holoenzyme, whereas ATP stabilizes the holoenzyme complex against dissociation. The Peak II holoenzyme is not affected by either salt of histone and is only dissociated by cyclic AMP. Once dissociated, the subunits of Peak II will rapidly reassociate under low salt conditions whereas the subunits of Peak I will not reassociate. By utilizing the distinct properties of Peak I and Peak II, it is possible to demonstrate the activation of both Peak I and Peak II Sertoli cell protein kinase in response to FSH.
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PMID:Characterization and follicle stimulating hormone activation of Sertoli cell cyclic AMP-dependent protein kinases. 19 15

The endogenous protein-phosphorylating activity of isolated chromatin was tested. We have found that a group of high-molecular-weight proteins (Mr greater than 50 000) was preferentially phosphorylated when chromatin from mouse ascites cells or from bovine lymphocytes was incubated in the presence of ATP. After disintegration of chromatin by nuclease treatment or by high salt concentration, a larger spectrum of chromatin proteins becomes accessible for phosphorylation by the chromatin-bound protein kinase. Some observations described in this communication may help to partially explain this result. The protein kinase was not found in nucleosomal subunits, indicating a non-random distribution of the enzyme in chromatin. This suggests that enzyme and substrate have to be in close spatial contact for the phosphorylation reaction to occur. Furthermore, we have shown for one protein, histone H1, that phosphorylation sites for the endogenous protein kinase are available on the free but not on the DNA-bound protein, suggesting that phosphate-accepting sites in chromatin proteins may be blocked by protein-DNA or by protein-protein interactions. We also discuss the possibility that chromatin protein kinase occurs in stable complexes with its phosphate-accepting substrates, as has been suggested by the findings of other [Kish, V.M. & Kleinsmith, L.J. (1974) J. Biol. Chem. 249, 750-760].
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PMID:Studies on protein-phosphorylation reactions in isolated chromatin. 19 26

Five peaks of cyclic AMP-binding activity could be resolved by DEAE-cellulose chromatography of bovine adrenal-cortex cytosol. Two of the binding peaks co-chromatographed with the catalytic activities of cyclic AMP-dependent protein kinases (ATP-protein phosphotransferase, EC 2.7.1.37) of type I or type II respectively. A third binding protein was eluted between the two kinases, and appeared to be the free regulatory moiety of protein kinase I. Two of the binding proteins for cyclic AMP, sedimenting at 9S in sucrose gradients, could also bind adenosine. They bound cyclic AMP with an apparent equilibrium dissociation constant (K(d)) of about 0.1mum, and showed an increased binding capacity for cyclic AMP after preincubation in the presence of K(+), Mg(2+) and ATP. The two binding proteins differed in their apparent affinities for adenosine. The isolated regulatory moiety of protein kinase I had a very high affinity for cyclic AMP (K(d)<0.1nm). At low ionic strength or in the presence of MgATP, the high-affinity binding of cyclic AMP to the regulatory subunit of protein kinase I was decreased by the catalytic subunit. At high ionic strength and in the absence of MgATP the high-affinity binding to the regulatory subunit was not affected by the presence of catalytic subunit. Under all experimental conditions tested, dissociation of protein kinase I was accompanied by an increased affinity for cyclic AMP. To gain some insight into the mechanism by which cyclic AMP activates protein kinase, the interaction between basic proteins, salt and the cyclic nucleotide in activating the kinase was studied.
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PMID:Binding proteins for adenosine 3':5'-cyclic monophosphate in bovine adrenal cortex. 20 Feb 26

The protein-bound cyclic AMP and the activity of cytosolic protein kinases in the presence and absence of cyclic AMP were determined in rat liver up to 2h after injection of glucagon. On the basis of the different salt-sensitivities of the activated cyclic AMP-dependent proteinkinases I and II, an activation of protein kinase II restricted to the high cyclic AMP concentrations present in the first 30 min after hormone injection was found. Essentially the same result was obtained by chromatographic analysis on DEAE-cellulose of liver cytosol from untreated rats and from rats killed at 2 and 60 min after glucagon injection. Protein kinase II activation was only detected at 2 min after injection. In contrast, the cyclic AMP-dependent protein kinase I was found to be nearly totally activated at 2 min and to be still almost as active at 60 min after the hormone stimulus, whereas the amount of bound cyclic AMP and the activation of total cytosolic protein kinases had fallen to two-thirds of their maximal values during this time period. A third cyclic AMP-independent protein kinase, which co-chromatographed with protein kinase type II, could be clearly distinguished from the two cyclic AMP-dependent kinases by use of the heat-stable inhibitor from bovine muscle, which totally inhibited the cyclic AMP-dependent enzymes, but stimulated the cyclic AMP-independent protein kinase.
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PMID:Differential activation of type-I and type-II adenosine 3':5'-cyclic monophosphate-dependent protein kinases in liver of glucagon-treated rats. 20 61

Plasma membranes can be isolated without disruption of cells by the plasma membrane vesiculation technique (Scott, R.E. (1976) Science 194, 743-745). A major advantage of this technique is that it avoids contamination of plasma membranes with intracellular membrane components. Using this method, we prepared plasma membranes from L6 myoblasts grown in tissue culture and studied the characteristics of the protein phosphorylation system. We found that these plasma membrane preparations contain protein kinase which is tightly bound to the membrane and cannot be removed by washing in EDTA or in high ionic strength salt solutions. This protein kinase activity can catalyze the phosphorylation of several exogenous substrates with decreasing efficiency as acceptors of phosphate: calf thymus histones f2b, protamine and caseine. Cyclic AMP causes a dose-dependent stimulation of protein kinase activity; the highest stimulation (4-fold) is achieved at concentration 10(-5) M cyclic AMP. Cyclic AMP-dependent stimulation can be completely inhibited by heat-stable protein kinase inhibitor isolated from rabbit skeletal muscle. On the other hand, cyclic GMP does not affect the activity of protein kinase. Plasma membrane-bound protein kinase also catalyzes the phosphorylation of endogenous membrane protein substrates and this is also stimulated by addition of cyclic AMP. Analysis of plasma membrane proteins by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis showed that specific polypeptides are phosphorylated by cyclic AMP-independent and by cyclic AMP-dependent protein kinase systems. The results of these studies demonstrate the presence of endogenous cyclic AMP-dependent and -independent protein phosphorylating systems (enzyme activity and substrates) in purified plasma membrane preparations. These data provide a basis for further investigations on the role of plasma membrane phosphorylation as a regulator of membrane functions including those that may control cellular differentiation.
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PMID:Plasma membrane cyclic AMP-dependent protein phosphorylation system in L6 myoblasts. 20 25


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