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 protein kinase phosphorylating sea urchin spermatogenous histones, H1 and H2B, was found in sea urchin egg homogenate and purified. The kinase is activated by cAMP and is composed of two different types of subunits with molecular masses 41 and 46 kDa. The kinase phosphorylates a peptide, Ser-Pro-Arg-Lys-Ser-Pro-Arg-Lys, which is a double repeat of the DNA-binding SPKK motif [Suzuki M., (1989) EMBO J. 8, 797-804]. We name this kinase SPkinase because it exclusively phosphorylates H1 and H2B, the only histones containing SPKK motifs. Phosphorylation of H1 by SPkinase decreases the DNA-binding ability of H1. This paper is the first to report purification of a kinase which affects the DNA-binding ability of a gene regulatory protein.
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PMID:Histone H1 kinase specific to the SPKK motif. 217 68

A meiosis-activated myelin basic protein (MBP) kinase was purified approximately 8700-fold from soluble post-germinal vesicle breakdown extracts from maturing oocytes of the sea star Pisaster ochraceus. Purification to apparent homogeneity was achieved by sequential chromatography on DEAE-cellulose, hydroxylapatite, phosphocellulose, phenyl-Sepharose, heparin-Sepharose, polylysine-Sepharose, and Mono-Q. The final product exhibited an apparent molecular mass of approximately 42 kDa by both native gradient and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and this precisely correlated with the chromatographic behavior of the recovered MBP kinase activity on a Superose 6/12 column. The kinase utilized the MBP as the major substrate with little or no phosphorylation of histones (H1, H2A, or H2B), casein, phosvitin, protamine, or 40 S ribosomal proteins. The purified enzyme was relatively insensitive to high concentrations of beta-glycerol phosphate, calmodulin, EGTA, NaCl, sodium fluoride, dithiothreitol, spermine, and heparin but was quite sensitive to inhibition by metal ions such as Mn2+, Zn2+, and Ca2+. The true Km values for ATP and myelin basic protein were determined to be 58 and 25 microM, respectively, using double-reciprocal plots. The purified enzyme was unable to utilize GTP in place of ATP. The enzyme was shown to rapidly undergo autophosphorylation. The autophosphorylation was sensitive to alkali treatment implying that phosphate was incorporated on serine/threonine residues. The properties of this MBP kinase are reminiscent of a protein kinase that is also activated in a cyclic fashion at M-phase during the early cell divisions of sea star and sea urchin embryos (Pelech, S. L., Tombe, R., Meijer, L., and Krebs, E. G. (1988) Dev. Biol. 130, 26-36).
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PMID:Purification and characterization of a maturation-activated myelin basic protein kinase from sea star oocytes. 229 20

Sea urchin sperm-specific histones H1 and H2B have distinctive N-terminal, and in the case of H1 also C-terminal, domains containing repeats of a basic motif (-Ser-Pro-Lys/Arg-Lys/Arg- or a closely related sequence). The histones in spermatids (the precursors of sperm) are phosphorylated, and the unphosphorylated histones of mature sperm are rephosphorylated upon fertilization. These changes correlate with finely tuned changes in chromatin packing in the nucleus, and the domains responsible are evidently the N-terminal domains. We show that in spermatids there are six tandemly repeated phosphorylation sites in the N-terminal domain of H1 (a typical cAMP dependent protein kinase site is not phosphorylated) and that H2B is phosphorylated in the N-terminal domain at two or three sites in the case of H2B1 and four sites in H2B2. The consensus sequence for phosphorylation is -Ser-Pro-X-Lys/Arg-, where X is Thr, Gln, Lys or Arg. There is an additional phosphorylated site in the C-terminal domain of H1 but most (or possibly all) copies of the consensus motif, which are here dispersed, are not phosphorylated. The negative charge introduced upon phosphorylation would be expected to weaken or abolish electrostatic interaction with DNA of this motif, which also occurs, and is phosphorylated, in somatic H1s.
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PMID:Phosphorylation at clustered -Ser-Pro-X-Lys/Arg- motifs in sperm-specific histones H1 and H2B. 231 83

It has previously been demonstrated that calmodulin can be phosphorylated in vitro and in vivo by both tyrosine-specific and serine/threonine protein kinase. We demonstrate here that the insulin receptor tyrosine kinase purified from human placenta phosphorylates calmodulin. The highly purified receptors (prepared by insulin-Sepharose chromatography) were 5-10 times more effective in catalysing the phosphorylation of calmodulin than an equal number of partially purified receptors (prepared by wheat-germ agglutinin-Sepharose chromatography). Phosphorylation occurred exclusively on tyrosine residues, up to a maximum of 1 mol [0.90 +/- 0.14 (n = 5)] of phosphate incorporated/mol of calmodulin. Phosphorylation of calmodulin was dependent on the presence of certain basic proteins and divalent cations. Some of these basic proteins, i.e. polylysine, polyarginine, polyornithine, protamine sulphate and histones H1 and H2B, were also able to stimulate the phosphorylation of calmodulin via an insulin-independent activation of the receptor tyrosine kinase. Addition of insulin further increased incorporation of 32P into calmodulin. The magnitude of the effect of insulin was dependent on the concentration and type of basic protein used, ranging from 0.5- to 9.0-fold stimulation. Maximal phosphorylation of calmodulin was obtained at an insulin concentration of 10(-10) M, with half-maximal effect at 10(-11) M. Either Mg2+ or Mn2+ was necessary to obtain phosphorylation, but Mg2+ was far more effective than Mn2+. In contrast, maximal phosphorylation of calmodulin was observed in the absence of Ca2+. Inhibition of phosphorylation was observed as free Ca2+ concentration exceeded 0.1 microM, with almost complete inhibition at 30 microM free Ca2+. The Km for calmodulin was approx. 0.1 microM. To gain further insight into the effects of basic proteins in this system, we examined the binding of calmodulin to the insulin receptor and the polylysine. Calmodulin binds to the insulin receptor in a Ca2+-dependent manner, whereas it binds to polylysine seemingly by electrostatic interactions. These studies identify calmodulin as a substrate for the highly purified insulin receptor tyrosine kinase of human placenta. They also demonstrate that the basic proteins, which are required for insulin to stimulate the phosphorylation of calmodulin, do so by a direct interaction with calmodulin.
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PMID:Tyrosine-specific phosphorylation of calmodulin by the insulin receptor kinase purified from human placenta. 248 Jul 80

Since the studies on tyrosine phosphorylation of calmodulin by the insulin receptor kinase in vitro suggested that protamine and poly(L-lysine) may activate phosphorylation of the receptor beta subunit [Sacks & McDonald (1988) J. Biol. Chem. 263, 2377-2383], we examined the effects of a variety of basic polycations/proteins and polyamines on insulin receptor kinase activity. The insulin receptor purified from human placental membranes was incubated with each basic polycation/protein or polyamine and assayed for tyrosine-specific protein kinase activity by measuring 32P incorporation into the src-related peptide. At a concentration of 1 microM, poly(L-lysine) and poly(L-ornithine) markedly stimulated kinase activity, whereas poly(L-arginine) and histones H1 and H2B inhibited insulin receptor kinase. In contrast, at a concentration of 1 mM, three polyamines (spermine, spermidine and putrescine) did not alter kinase activity. Poly(L-lysine) and poly(L-ornithine) stimulated the insulin receptor kinase by 5-10-fold at concentrations of 0.1-1 microM. Protamine sulphate also showed a significant stimulatory effect at a concentration of 100 microM. Preincubation of the receptor with poly(L-lysine) or poly(L-ornithine) for 20-60 min resulted in maximal kinase activation. Poly(L-lysine), the most effective activator of the receptor kinase, was used to characterize further the mechanisms of the kinase activation. Poly(L-lysine) activates the insulin receptor kinase by increasing the Vmax. without changing the Km. Poly(L-lysine) markedly stimulates the kinase activity of insulin receptor preparations that have lost both basal kinase activity and the ability to be stimulated by insulin. Insulin and poly(L-lysine) also differed in their ability to stimulate the kinase activity of prephosphorylated receptors. Prephosphorylation of the receptors did not affect the stimulation of the kinase by insulin. In contrast, prephosphorylation of receptors resulted in a markedly enhanced ability of poly(L-lysine) to stimulate kinase activity. These studies suggest that the mechanisms by which poly(L-lysine) and insulin activate the kinase are different. In conjunction with other additional evidence, it is suggested that poly(L-lysine) interacts directly with the beta-subunit of the receptor, thereby activating the receptor kinase.
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PMID:Effect of basic polycations and proteins on purified insulin receptor. Insulin-independent activation of the receptor tyrosine-specific protein kinase by poly(L-lysine). 255 12

S6 kinase activity was increased in the regenerating liver 5 h after partial hepatectomy compared with sham-operated liver. The protein kinase activity was eluted from DE-52 column at approximately 250 mM NaCl and was not affected by known regulators of protein kinases. The S6 kinase was further purified by chromatography on peptide R1A13-Sepharose 4B and Sephadex G-150. The molecular weight of the enzyme was estimated to be 4.5 X 10(4) by gel filtration. The enzyme catalyzes the phosphorylation of whole histone, mainly H2B histone, at 75 mM Mg2+. These properties are similar to those of a proteolytically modified Ca2+/phospholipid-independent form of protein kinase C.
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PMID:An activated S6 kinase in regenerating rat liver. 360 18

A protein kinase system with unusual characteristics was noted in extracts of HL-60 cells using endogenous proteins as substrates. This system exhibited a cation preference for manganese at an optimal concentration of 0.5 mM. Moderate activity was detectable with magnesium at an optimal concentration of 5.0 mM, but calcium was inactive. Activity was markedly stimulated by phospholipid, with phosphatidylglycerol and phosphatidylinositol exhibiting greater activity than phosphatidylserine. In isolated plasma membranes, the major substrate of this system was a 73-kDa protein, while cytoplasmic extracts exhibited larger amounts of a 42-kDa substrate. 73-kDa phosphorylating activity of membranes was comparably active at 0 and 31 degrees C, although in cytosol activity was greater at 31 degrees C. No 73-kDa protein phosphorylation was observed in the presence of Ca2+, Mg2+, and phosphatidylserine. Phosphoamino acid analysis of the 73-kD band revealed phosphothreonine and phosphoserine. The 42-kDa substrate was distinguishable from actin by two-dimensional gel electrophoresis, which disclosed that both major substrates were highly basic in the isoelectric focusing dimension. Protamine and histones (H2B greater than H1 greater than H3) exhibited phospholipid-stimulated phosphorylation in the presence of Mn2+, but phosvitin, casein, and vinculin were not substrates. High levels of phosphorylative activity involving the 73-kDa substrate were noted in nuclear extracts. Complex patterns of increase of this activity were noted in both cytosol and nuclear extracts following induction of differentiation with dimethyl sulfoxide, retinoic acid, or phorbol 12-myristate 13-acetate. This study thus demonstrated the presence of a previously undescribed type of protein kinase activity which exhibited alterations during leukemic cellular differentiation.
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PMID:Manganese-phospholipid-stimulated protein kinase activity of human leukemic cells. 385 77

Subcellular fractionation of rat and human cells transformed by the adenovirus type 12 (Ad-12) EcoRI-C DNA fragment showed that the 41000 mol. wt. (41K) E1a and 52K E1b proteins were present in the nucleus and cytoplasm at approximately equal concentrations. The 18K E1b protein was associated with the nuclear, mitochondrial, lysosomal and membrane fractions. The 41K E1a protein was also associated with various cytoskeletal structures (probably microtubules and 10 nm filaments) in Ad-12-transformed cells. The Ad-12 E1 41K and 52K proteins have been partially purified from transformed and infected cells. Using these preparations the 52K protein has been shown to exist under non-reducing conditions and probably in vivo as a 100K dimer stabilized by intermolecular disulphide bonds. The 41K protein bound strongly to histones H1 and H4 but much more weakly to H2A, H2B and H3. It did not interact with other comparable basic proteins or with the cytoskeletal components actin, tropomyosin and calmodulin. Although the 41K E1 a protein bound to histones in vitro it is probable that such an interaction may not occur in vivo as very little of the adenovirus protein co-purified with chromatin from transformed cells. None of the Ad-12 E1 proteins showed any ATPase or protein kinase activity.
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PMID:Adenovirus type 12 early region 1 proteins: a study of their subcellular localization and protein-protein interactions. 623 9

Interaction of cGMP-dependent protein kinase with histones H2A, H2B, H3, and H4, or poly(L-arginine) resulted in changes in enzyme conformation such that inactivation of cGMP binding and activation of basal catalytic activity (assayed without cGMP) occurred. Total kinase activity as determined by phosphorylation of exogenous substrates subsequently decreased, but autophosphorylation of the enzyme was enhanced. The reaction was specific for nucleosome core histones and poly(L-arginine); H1, troponin, and poly(L-lysine) had no effect. Inactivation of cyclic nucleotide binding sites followed pseudo-first order kinetics and, at various histone concentrations, exhibited saturation kinetics at low ionic strength (2 mM potassium phosphate, pH 6.8), but non-saturation kinetics at higher ionic strength (37.5 mM potassium phosphate, pH 6.8, 12.5 mM MgCl2). Saturation kinetics was observed with poly(L-arginine) at both low and high ionic strength. Kinetic parameters measured under saturation conditions were determined for each core histone and poly(L-arginine). Core histones and poly(L-arginine) were noncompetitive inhibitors of cGMP binding; core histones and poly(L-arginine) interacted competitively at an enzyme site designated as the poly(L-arginine) binding site. Regulatory subunits of cAMP-dependent protein kinase contain a similar poly(L-arginine) binding site. Modulator proteins bind to poly(L-arginine) or arginyl residues in histone to prevent interaction with the poly(L-arginine) binding site on the enzymes. Through this mechanism, modulator proteins maintain cyclic nucleotide dependency and full enzyme activity.
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PMID:Regulation of cyclic nucleotide-dependent protein kinase activity by histones and poly(L-arginine). 625 84

Under certain physiological conditions a change in the phosphorylation of histones in mouse epidermis in vivo was observed. Thus a single local application of the tumor-promoting mitogen 12-O-tetradecanoylphorbol-13-acetate caused a long-lasting increase of histone H1 phosphorylation which paralleled stimulated cell proliferation. Injection of the antimitotic beta-adrenergic agonist isoproterenol led to a temporary decrease in the rate of phosphorylation of H1, H2A and H2B immediately after cyclic AMP accumulation. A complete protein phosphorylation system could be demonstrated in mouse epidermis homogenates. The following enzyme activities were partially purified and characterized: a cyclic AMP-dependent histone kinase; a 'casein kinase' and an 'unspecific' protein kinase; a histone-specific protein phosphatase; and two 'unspecific' phosphoprotein phosphatases. In addition, a stimulatory effect of cyclic GMP on histone phosphorylation was observed. The enzymes were found to be predominantly localized in the 105000 X g supernatant, but a small proportion of protein kinase and phosphatase activity could be regularly demonstrated in cell nuclei.
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PMID:Histone phosphorylation in phorbol ester stimulated and beta-adrenergically stimulated mouse epidermis in vivo and characterization of an epidermal protein phosphorylation system. 626 86


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