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 protein kinase associated with purified virions of avian myeloblastosis BAI strain A was partially purified by ion-exchange chromatography and gel filtration. The transfer of phosphate catalyzed by this enzyme required a divalent metal ion and ATP as phosphate donor. GTP could not be substituted for ATP, and the reaction was unaffected by either cyclic AMP or beef-heart protein-kinase inhibitor. Of the virus and nonvirus proteins tested as phosphate acceptors, only acidic proteins were phosphorylated. In particular, purified preparations of reverse transcriptase from avian myeloblastosis virus did not accept phosphate. The enzyme is a basic protein (pI = 9.3), and, on the basis of molecular sieving through Sephadex G-200 and velocity sedimentation on glycerol gradient, the protein kinase has a molecular weight of 45,000.
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PMID:Protein kinase from avian myeloblastosis virus. 2 25

The protein kinase activities of a transplantable, insulin-producing hamster islet cell tumor were characterized using gel filtration, sucrose density gradient centrifugation and acrylamide gel electrophoresis. The post-microsomal supernatant fluid contains 70-80% of the protein kinase activity present in crude homogenates. A cAMP-dependent protein kinase, PK I (Mr 170,000), represents 25% of the soluble protein kinase activity assayed with protamine as substrate. It dissociates in the presence of cAMP into a cAMP-binding protein, R2 (Mr 90,000) and a catalytic subunit C (Mr 33,000). The dissociation induced by cAMP seems to be facilitated by the addition of Mg2+ and ATP. The regulatory subunit, R2, changes its gel filtration pattern in the presence of 0.5 M NaCl suggesting dissociation into a smaller subunit, R1 (Mr 44,000). By analogy with purified beef heart protein kinase (Erlichman et al., 1973) and skeletal muscle protein kinase, PK I. The presence in crude homogenates of a free cAMP-binding protein indistinguishable from the R2 derived by dissociation of PK I, suggests that PK I is partially dissociated in vivo. A cAMP-independent (casein) kinase (Mr 210,000) elutes with PK I on columns of Sepharose 6B. Another cAMP-independent protein kinase, PK II (Mr 88,000), is the predominatn form of soluble protein kinase accounting for approximately 75% of the soluble protein kinase activity detected using protaimine as substrate. This cAMP-independent protein kinase changes its gel filtration pattern in the presence of 0.5 M NaCl giving rise to a form which appears to have the same Mr (33,000) as the catalytic subunit of PK I. Studies comparing the catalytic subunit C of PK I with PK II and its salt-induced smaller molecular form demonstrate facile association of C with the cAMP-binding protein of purified bovine heart protein kinase to yield a hybrid holoenzyme, whereas PK II and its smaller form fail to recombine in this fashion. The 33,000 dalton forms derived from PK I (by cAMP) and PK II (by salt) also show different substrate specificities. It would appear, therefore, that pK II is a cAMP-independent protein kinase unrelated to PK I.
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PMID:Characterization of the protein kinases in a transplantable islet cell tumor of the Syrian hamster. 17 65

The effects of adenosine 3' : 5'-monophosphate (cyclic AMP), guanosine 3' : 5'-monophosphate (cyclic GMP) and exogenous protein kinase on Ca uptake and membrane phosphorylation were studied in subcellular fractions of vascular smooth muscle from rabbit aorta. Two functionally distinct fractions were separated on a continuous sucrose gradient: a light fraction enriched in endoplasmic reticulum (fraction E) and a heavier fraction containing mainly plasma membranes (fraction P). While cyclic AMP and cyclic GMP had no effect on Ca uptake in the absence of oxalate, both cyclic nucleotides inhibited the rate of oxalate-activated Ca uptake when used at concentrations higher than 10(-5) M. The addition of bovine heart protein kinase to either fraction produced an increase in the rate of oxalate-activated Ca uptake which was further augmented by cyclic AMP. Cyclic GMP caused smaller stimulations of protein kinase-catalyzed Ca uptake than cyclic AMP. Mg-dependent phosphorylation, attributable to endogenous protein kinase(s), was inhibited in fraction E by low concentrations (10(-8) M) of both cyclic AMP and cyclic GMP. In fraction P, an inhibition by cyclic AMP occurred also at a concentration of 10(-8) M, while with cyclic AMP a concentration of 10(-5) M was required for a similar inhibition. Bovine heart protein kinase stimulated the phosphorylation of the membrane fractions much more than Ca uptake. In fraction E, in the presence of bovine protein kinase, both cyclic AMP and cyclic GMP stimulated phosphorylation up to 200%. Under these conditions, no stimulation was observed in fraction P. These results are compatible with the hypothesis that in vascular smooth muscle soluble rather than particulate protein kinases are involved in the regulation of intracellular Ca concentration.
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PMID:Effects of adenosine 3' : 5'-monophosphate and guanosine 3' : 5'-monophosphate on calcium uptake and phosphorylation in membrane fractions of vascular smooth muscle. 21 15

Studies on the gonadotrophin-responsive adenylyl cyclase (AC) system of rabbit and porcine ovarian follicles reveal that hCG or LH-induced desensitization of the AC system can be divided into two phases: an initial, LH-specific phase and a second phase which is not specific for LH. The first phase occurs within the first hour after LH-hCG-receptor interaction, is agonist specific, and is not mediated by protein synthetic events or by cAMP. In view of our previous demonstration of the critical dependence of the LH-induced desensitizing process in cell-free membrane preparations of porcine follicles upon Mg2+ and ATP, we investigated the role of a phosphorylation reaction in the first phase of the AC desensitizing process. Porcine follicular membranes rich in LH-sensitive AC activity were found to contain the molecular requirements necessary for a phosphorylation reaction: namely, cAMP-dependent and cAMP-independent protein kinases as well as phosphoprotein phosphatases. The following lines of indirect evidence indicated that reversal or resensitization of the desenzitized AC system to LH was mediated by a dephosphorylation reaction. Activators of endogenous phosphoprotein phosphatases--Mn2+ and dithiothreitol--promoted a specific resensitization of the follicular AC system to LH. Likewise, a partially purified phosphoprotein phosphatase also resensitized the desensitized, LH unresponsive AC to LH, and boiling of the phosphatase prevented its effect. LH-induced desensitization of the AC system, on the other hand, did not appear to be mediated by a cAMP-dependent protein kinase, as evidenced both by the inability of beef heart protein to promote desensitization of AC and by the inability of an inhibitor of cAMP-dependent protein kinase to prevent LH-induced densensitization. The second phase of desensitization, which occurs after the first hour following hCG-LH-receptor interaction, is characterized by a loss of responsiveness to FSH as well as to LH and can be promoted by dibutryl cAMP (in the absence of LH). These results provide new evidence on the characteristics and molecular mechanism of LH-induced densensitization of the follicular AC system. These results indicate that the level of phosphorylation of membrane-associated components may, in part, regulate the activity of the AC system during this first phase of homologous desensitization.
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PMID:LH-induced desensitization of the adenylyl cyclase system in ovarian follicles. 22 90

Meiosis reinitiation has been triggered by injection of beef heart protein kinase or rabbit phosphorylase kinase into Xenopus laevis oocytes. Successful injections are followed by germinal vesicle breakdown, chromosome condensation, formation of a normal meiotic spindle, and appearance of an amplifiable maturation promoting factor. Meiosis reinitiation does not occur when the enzymes are introduced into the oocytes simultaneously with EGTA or after pretreatment with cycloheximide. Antipain, an antiprotease which abolishes the response of oocytes to progesterone, does not suppress the meiosis reinitiation induced by injection of protein kinase or phosphorylase kinase.
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PMID:Induction of meiosis by injection of heterologous protein kinase and phosphorylase kinase in Xenopus laevis oocytes. 96 20

Phosphatidate-dependent protein phosphorylation was observed in soluble extracts from rat liver, brain, lung, and testis. The phosphorylation was stimulated by free Ca2+ in the range of 360-800 nM. Incubation mixtures containing phosphatidate provided markedly different profiles of protein phosphorylation from those with phosphatidylserine plus 1,2-diolein. Phosphatidate-dependent phosphorylation of a 30-kDa protein in the soluble fraction from heart was also observed. This phosphorylation did not require Ca2+. Soluble fractions from liver, testis, brain, and lung phosphorylated the 30-kDa heart protein in a phosphatidate-dependent Ca(2+)-independent manner. We propose that part of the action of phosphatidate in cells may be mediated by a protein kinase(s).
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PMID:Phosphatidate-dependent protein phosphorylation. 206 2

A cAMP-dependent protein kinase from mycelia of Saccobolus platensis was characterized. The holoenzyme seems to be a dimer (i.e., regulatory subunit--catalytic subunit) of 78,000 Da, slightly activated by cAMP but susceptible to dissociation into its subunits by cAMP, or by kemptide and protamine, the best substrates for Saccobolus protein kinase. The regulatory subunit was purified to homogeneity by affinity chromatography. It is highly specific for cAMP and has two types of binding sites but failed to inhibit the phosphotransferase activity of the homologous or the heterologous (bovine heart) catalytic components. The activity of the catalytic subunit was completely abolished by the regulatory component of the bovine heart protein kinase as well as by a synthetic peptide corresponding to the active site of the mammalian protein kinase inhibitor. The data suggest that interaction between the subunits of the S. platensis protein kinase is different than that found in cAMP-dependent protein kinases from other sources. Similarities and differences between the Saccobolus protein kinase and enzymes from low eucaryotes and mammalian tissues are discussed.
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PMID:Isolation and characterization of a dimeric cAMP-dependent protein kinase from the fungus Saccobolus platensis. 217 26

Partial activation of Mucor rouxii cAMP-dependent protein kinase by cAMP was obtained when kemptide was used as substrate, but complete activation was attained with cAMP plus protamine or histone. Full activation could not be achieved by increasing kemptide or cAMP concentration. Complete activation by cAMP could be obtained by addition of 10 microM polylysine, 10 microM lysine-rich histone or 0.5 mM spermine plus spermidine. The degree of stimulation could be up to 5-fold, depending on the amount of enzyme in the assay. The same concentrations of polycations increased 1.5-2.3-fold the Vmax of kemptide phosphorylation by the free catalytic subunits of both Mucor and bovine heart protein kinases; 10 microM polyarginine inhibited completely the activity of both enzymes.
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PMID:Polyamines and basic proteins stimulate activation by cAMP and catalytic activity of Mucor rouxii cAMP-dependent protein kinase. 217 92

cDNA clones coding for the regulatory subunit (RII beta) of type II cAMP-dependent protein kinase were isolated from a bovine brain cDNA expression library in lambda gt11. The cDNA codes for a protein of 418 amino acids which is 98% homologous to the rat and human RII beta proteins. A series of expression vectors coding for truncated RII beta proteins were constructed in pATH plasmids and fusion proteins were expressed in Escherichia coli. Polyclonal and monoclonal antibodies made against purified bovine brain RII were immunoreactive with the fusion proteins on Western blots. The expressed RII beta-fusion proteins were used in overlay assays to identify the region in RII beta which binds to microtubule-associated protein 2 (MAP2) and to the 75,000-dalton calmodulin-binding protein (P75) (Sarkar, D., Erlichman, J., and Rubin, C.S. (1984) J. Biol. Chem. 259, 9844-9846) in bovine brain. Fusion protein containing amino acids 1-50 of the RII beta NH2 terminus (RII beta(1-50)] bound to both MAP2 and P75 immobilized on nitrocellulose filters. A pATH11-directed fusion protein containing the 31 amino acid RII-binding site of the human MAP2 protein (MAP2(31)) (Rubino, H.M., Dammerman, M., Shafit-Zagardo, B., and Erlichman, J. (1989) Neuron 3, 631-638) also bound RII beta-fusion proteins containing RII beta amino acids 1-50. Three fusion proteins, RII beta(1-25), RII beta(25-96), and RII beta(1-265,25-96 deleted) did not bind to MAP2(31) nor P75. The results showed that the binding domain for MAP2 and P75 was located within the NH2-terminal 50 amino acids of RII beta. Preincubation of bovine heart protein kinase II alpha and RII beta(1-50) with MAP2(31) prevented their binding to both P75 and MAP2(31) that were immobilized on nitrocellulose, suggesting that the binding sites for MAP2 and P75 are located near each other or that the same site on RII was binding to both proteins.
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PMID:Identification of the MAP2- and P75-binding domain in the regulatory subunit (RII beta) of type II cAMP-dependent protein kinase. Cloning and expression of the cDNA for bovine brain RII beta. 225 32

Protein kinase was isolated from both amastigotes and promastigotes of Leishmania mexicana amazonensis. Unlike the previously described enzyme from L. donovani promastigotes, activity of the L. mexicana kinases was 2-3 times higher at low ionic strength than at high ionic strength, and was 3-10-fold augmented by removal of endogenous low molecular weight inhibitors. The Km of the L. mexicana kinases was 123-223 microM, compared to the value of 70 microM for the beef heart kinase. Purine nucleoside analogs are potent antileishmanial agents that are phosphorylated to their respective triphosphates. The mechanism of the analogs is thought to involve competition of the triphosphates with ATP. Cordycepin triphosphate inhibited the amastigote, promastigote, and beef heart protein kinases approximately equally. However, the Kis of formycin A triphosphate for the leishmanial kinases (Ki 40-120 microM) were far less than that of the beef heart kinase (Ki 1,380 microM). The mechanisms of certain chemotherapeutic purine nucleosides may involve specific inhibition of leishmanial protein kinase by the nucleoside triphosphate.
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PMID:Inhibition of leishmanial protein kinase by antileishmanial drugs. 283 26


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