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)

Rat liver mitochondria were subfractionated into outer membrane, intermembrane and mitoplast (inner membrane and matrix) fractions. Of the recovered protein kinase activity, 80-90% was found in the intermembrane fraction, while the rest was associated with mitoplasts. The intermembrane protein kinase was stimulated by cyclic AMP, while the mitoplast enzyme was stimulated by the nucleotide only after treatment with Triton X-100. Extracted protein kinase resolved into three peaks on DEAE-cellulose chromatography. All three peaks were present both in the intermembrane fraction and in mitoplasts. One peak corresponded to the catalytic subunit of cyclic AMP-dependent protein kinases, one was a cyclic AMP-independent enzyme, and the third was the cyclic AMP-dependent type II enzyme. The endogenous incorporation of phosphate was particularly high in the outer mitochondrial membrane, and occurred also in the mitoplast fraction. The incorporation in mitoplasts was to a double band of Mr 47 500, and in outer membranes to apparently heterogeneous material of comparatively low molecular weight.
Biochim Biophys Acta 1979 Dec 11
PMID:Protein kinase activity and endogenous phosphorylation in subfractions of rat liver mitochondria. 50 12

The protein synthesis initiation factor eIF-3 (a multicomponent protein complex) was labelled with 32P by phosphorylation with a protein kinase present in a partially purified 'hemin-controlled repressor' preparation. The interaction of the labelled factor with the 40 S ribosomal subunit during the course of initiation was followed. It binds to the 40 S subunit in the absence of other initiation factors and inhibits the Mg2+-dependent reassociation of the 40 S with the 60 S ribosomal subunit. It stimulates the binding of the ternary complex (eIF-2, GTP, Met-tRNAf) to the 40 S subunit, and earlier work (Trachsel, H., Schreier, M.H., Erni, B. and Staehelin, T. (1977) J. Mol. Biol. 116, 745-767) also showed it to be essential for the subsequent binding of mRNA. The factor is released from the 40 S initiation complex during the 60 S subunit joining reaction.
Biochim Biophys Acta 1979 Dec 17
PMID:Initiation of mammalian protein synthesis. The multiple functions of the initiation factor eIF-3. 51 82

To ascertain the activity and substrate specificity of nuclear protein kinases during various stages of the cell cycle of HeLa S3 cells, a nuclear phospho-protein-enriched sample was extracted from synchronised cells and assayed in vitro in the presence of homologous substrates. The nuclear protein kinases increased in activity during S and G2 phase to a level that was twice that of kinases from early S phase cells. The activity was reduced during mitosis but increased again in G1 phase. When the phosphoproteins were separated into five fractions by cellulose-phosphate chromatography each fraction, though not homogenous, exhibited differences in activity. Variations in the activity of the protein kinase fractions were observed during the cell cycle, similar to those observed for the unfractionated kinases. Sodium dodecyl sulfate polyacrylamide gel electrophoretic analysis of the proteins phosphorylated by each of the five kinase fractions demonstrated a substrate specificity. The fractions also exhibited some cell cycle stage-specific preference for substrates; kinases from G1 cells phosphorylated mainly high molecular weight polypeptides, whereas lower molecular weight species were phosphorylated by kinases from the S, G2 and mitotic stages of the cell cycle. Inhibition of DNA and histone synthesis by cytosine arabinoside had no effect on the activity or substrate specificity of S phase kinases. Some kinase fractions phosphorylated histones as well as non-histone chromosomal proteins and this phosphorylation was also cell cycle stage dependent. The presence of histones in the in vitro assay influenced the ability of some fractions to phosphorylate particular non-histone polypeptides; non-histone proteins also appeared to affect the in vitro phosphorylation of histones.
Biochim Biophys Acta 1979 Dec 17
PMID:Nuclear protein kinase activities during the cell cycle of HeLa S3 cells. 51 84

Two-dimensional, high-resolution electrophoretic technique of O'Farrell has been adapted to the analysis of thyroid phosphorylated proteins. Proteins were extracted from dog thyroid slices which had been incubated in the presence of [32P]phosphate with thyrotropin or with different agents which enhance the intracellular accumulation of cyclic AMP. About 350 phosphorylated polypeptides have been separated. Thyrotropin stimulates the phosphorylation of at least eight of these polypeptides. An increase in the phosphorylation of the same polypeptides was observed was observed when dog thyroid slices were incubated with dibutyryl adenosine 3':5'-monophosphate, cholera toxin or prostaglandin E1 instead of thyrotropin. Our results confirm that most of dog thyroid protein phosphorylation is independent of cyclic AMP. They offer a first link between the action of cyclic AMP on protein kinase and the physiological effects of thyrotropin. They strongly substantiate the hypothesis that most thyrotropin effects are mediated by cyclic AMP.
Eur J Biochem 1979 Dec
PMID:Pattern of protein phosphorylation in intact stimulated cells: thyrotropin and dog thyroid. 52 Mar 19

The genetic basis of isozyme phenotypes of creatine kinase (CK) from extracts of skeletal muscle of salmonids has been resolved through breeding data including double heterozygous crosses and backcrosses of rainbow trout (Salmo gairdneri), and backcrosses of coho salmon (Oncorhynchus kisutch). The two-three-, or four-banded phenotypes of homozygous individuals and all heterozygous and hybrid phenotypes of ten salmonid species are readily explained by the following model: (1) there are no detectable heterodimers either between allelic products at a single locus or between loci: (2) each allele is represented electrophoretically by two bands, presumably a reflection of stable posttranslational modification of a single polypeptide unit; (3) CK of salmonid muscle is encoded by two loci--CK-1 and CK-2. The distance separating the paired bands reflecting each allele provides a basis for two groupings--a broad-spaced group (including all species of Oncorhynchus tested excepting O. masou) and a narrow-spaced group (including all species of Salmo tested and O. masou). The relationships among species suggested by the relative mobilities and spacings of these CK bands are consistent with taxonomic schemes inferred from morphological, cytogenetic, and other isozymic data.
Biochem Genet 1979 Dec
PMID:Genetic basis of creatine kinase isozymes in skeletal muscle of salmonid fishes. 54 1

Studies are presented on the influence of polyamines on prostatic chromatin- and non-histone-protein-associated protein kinase reactions involving both exogenous and endogenous substrates. The activities toward the model acidic protein substrate, dephosphophosvitin, were maximal at 160--200mM-NaCl (or -KCl or -NH4Cl). Under these conditions, spermidine and spermine added in concentrations up to 2mM were essentially without effect. However, without addition of NaCl to the medium, marked stimulation of these reactions was elicited by these polyamines at 1--2mM concentrations. The stimulatory effects were not due to non-specific changes in the ionic strength or to substitution of spermine for Mg2+, as maximal stimulation by 1 mM-spermine was observed only at optimal (2--4mM) Mg2+ concentrations. Qualitatively similar effects of polyamines were observed with enzyme preparations from the prostates of castrated rats, and with chromatin and non-histone-protein preparations from other tissues besides ventral prostate. When phosphorylation of endogenous non-histone proteins of the chromatin was measured, spermine stimulated both the initial rates and the final extent of transphosphorylation, even in the presence of optimal concentration of NaCl. By contrast, spermine or spermidine had no effect on the chromatin- and non-histone-protein-associated protein kinase reactions determined with lysine-rich histones as substrates. Chemically NN-dimethylated dephosphophosvitin was a less active substrate for the chromatin-associated protein kinase, but its phosphorylation was more markedly stimulated by spermine in comparison with unmodified dephosphophosvitin. These observations hint that the polyamine stimulations of the various protein kinase reactions may be due to effects on the conformations of the non-histone protein substrates rather than on the kinases themselves.
Biochem J 1978 Dec 15
PMID:Effects of polyamines on prostatic chromatin- and non-histone-protein-associated protein kinase reactions. 74 50

Hepatocytes isolated from the livers of fed rats were used for a comparative study of the effects of phenylephrine, vasopressin and glucagon on gluconeogenesis and on enzymes of glycogen metabolism. When hepatocytes were incubated in the presence of Ca(2+), phenylephrine stimulated gluconeogenesis from pyruvate less than did glucagon, but, in contrast with this hormone, it did not affect the activities of protein kinase and pyruvate kinase, nor the concentration of phosphoenolpyruvate, and it did not decrease the release of (3)H(2)O from [6-(3)H]glucose. The effects of vasopressin were similar to those of phenylephrine. Gluconeogenesis from fructose was also stimulated by phenylephrine and, more markedly, by glucagon at the expense of the conversion of fructose into lactate. Insulin was able to antagonize the stimulatory effect of phenylephrine on gluconeogenesis from pyruvate. When Ca(2+) was removed from the incubation medium, phenylephrine still stimulated gluconeogenesis from pyruvate, but it also caused an activation of protein kinase and an inactivation of pyruvate kinase; accordingly, the concentration of phosphoenolpyruvate was increased, and, in contrast, vasopressin had no effect on all these parameters. The property of phenylephrine to cause the activation of glycogen phosphorylase was decreased by glucose or by the absence of Ca(2+); it was abolished when these two conditions were combined. Glycogen synthase was inactivated by phenylephrine in the presence or the absence of Ca(2+), although presumably by different mechanisms.
Biochem J 1978 Dec 15
PMID:Control of gluconeogenesis and of enzymes of glycogen metabolism in isolated rat hepatocytes. A parallel study of the effect of phenylephrine and of glucagon. 74 52

Triiodothyronine (T3) administration to thyroidectomized rats induces a significant increase in the nucleolus-associated protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) activity. The general properties of the protein kinase solubilized from liver nucleoli have been investigated. Mg2+ (20 mM) is essential for the reaction and an appropriate concentration of NaCl (100 mM) is required to achieve maximal phosphorylation rates. The optimal pH for casein phosphorylation is 7.6. The kinase phosphorylates casein more efficiently than phosvitin and displays an almost undetectable activity towards histones and protamine. No significant stimulation of the kinase activity by cyclic AMP has been detected. The apparent Km values for casein and ATP are 1.5 mg/ml and 1.5-10(-5) M, respectively, and are not affected by the hormone administration.
Biochim Biophys Acta 1977 Dec 08
PMID:Increased activity of rat liver nucleolar protein kinase following triiodothyronine administration. 92 18

Autoactivation of phosphorylase kinase in the presence of substrates has been studied to determine the cause of the hysteresis, or lag, in the phosphorylase kinase reaction. Peptide analogs corresponding to the convertible serine region of phosphorylase have been used as low molecular weight alternative substrates. Autophosphorylation of the kinase molecule was measured under conditions that favored autoactivation. Phosphorylase b and a tetradecapeptide, which was found to be a good model of phosphorylase, stimulated autoactivation by 86- and 37-fold, respectively. The tetradecapeptide also stimulated autophosphorylation of subunits A and B of the kinase molecule. This increased autophosphorylation coincided with an increased ability to convert phosphorylase. This finding supports the hypothesis that autophosphorylation is responsible for the lag in the phosphorylase kinase reaction. No evidence was obtained to suggest that the lag could be due to dissociation of the kinase. The stoichiometry of phosphate incorporation into phosphorylase kinase subunits by autophosphorylation was much greater than that reported to occur by protein kinase phosphorylation. Multiple phosphorylation sites in subunit A accounted for most of the phosphate incorporation during autophosphorylation. Saturating levels of hexa- and octapeptide analogs also caused stimulation of autophosphorylation. Possible mechanisms and experimental implications of substrate-stimulated autophosphorylation are discussed. Consideration also is given to the possible role of effectors in autophosphorylation in vivo.
J Biol Chem 1976 Dec 10
PMID:Stimulation of phosphorylase kinase autophosphorylation by peptide analogs of phosphorylase. 100 97

Initiation factor IF-E2 was isolated from rabbit reticulocytes and purified 120-fold to near homogeneity by ammonium sulfate fractionation, column chromatography on DEAE-cellulose and phosphocellulose, and, when suitable, by sucrose density gradient centrifugation. The factor is a complex protein containing three nonidentical polypeptides of molecular weight 57,000, 52,000, and 36,000. It behaves as a complex throughout its purification and during polyacrylamide gel electrophoresis in nondenaturing buffer but its thress components are readily separated by electrophoresis in denaturing buffers. None of its components corresponds to any of the polypeptides of the other initiation factors or to any proteins of ribosomes washed in buffers containing a high salf concentration. A stoichiometric ratio of 1:1:1 was determined for the three polypeptides; based on the assumption of one copy each per complex, the calculated factor molecular weight is 145,000, a value in agreement with the measured value of 160,000. Initiation factor IF-E2 was radioactively labeled in vitro by reductive alkylation or by phosphorylation with a protein kinase also isolated from rabbit reticulocytes. Neither procedure causes a measurable change in the ability of the factor to form a ternary complex with GTP and the initiator methionyl-tRNA. 5'-Guanylyl-methylenediphosphonate may substitute for GTP, but only at relatively high concentrations. The binding of labeled initiation factor IF-E2 and methionyl-tRNA to the 40 S ribosomal subunit was studied by sucrose density gradient centrifugation. Appreciable binding of the factor is seen only when all three components of the ternary complex are included in the reaction mixture. The binding of either the factor or methionyl-tRNA was not stimulated by the addition of globin messenger RNA and initiation factor IF-E3. It was shown that all three polypeptide components of initiation factor IF-E2 are bound to these nascent initiation complexes.
J Biol Chem 1976 Dec 10
PMID:Purification and characterization of initiation factor IF-E2 from rabbit reticulocytes. 100 8


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