The CCR1 (SNF1) and SCH9 protein kinases act independently of cAMP-dependent protein kinase and the transcriptional activator ADR1 in controlling yeast ADH2 expression

1991 ◽  
Vol 229 (3) ◽  
pp. 395-399 ◽  
Author(s):  
Clyde L. Denis ◽  
Deborah C. Audino
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Transcriptional Activator ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

scholarly journals Insights into the phosphoryl transfer catalyzed by cAMP-dependent protein kinase

2014 ◽  
Vol 70 (a1) ◽  
pp. C449-C449
Author(s):  
Oksana Gerlits ◽  
Amit Das ◽  
Jianhui Tian ◽  
Malik Keshwani ◽  
Susan Taylor ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Active Site ◽  
Phosphate Group ◽  
Nucleoside Triphosphate ◽  
Phosphoryl Transfer ◽  
Hydrogen Atoms ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

Protein kinases are involved in a number of cell signaling pathways. They catalyze phosphorylation of proteins and regulate the majority of cellular processes (such as growth, differentiation, lipid metabolism, regulation of sugar, nucleic acid synthesis, etc.). Chemically, protein kinases covalently transfer the gamma-phosphate group of a nucleoside triphosphate (e.g. ATP) to a hydroxyl group of a Ser, Thr or Tyr residue of substrate protein or peptide. The reaction involves moving hydrogen atoms between the enzyme, substrate and nucleoside. The unanswered question is whether the proton transfer from the Ser residue happens before the phosphoryl transfer using the general acid-base catalyst, Asp166, or after the reaction went through the transition state by directly protonating the phosphate group. To address this key question about the phosphoryl transfer, we determined a number of X-ray structures of ternary complexes of catalytic subunit of cAMP-dependent protein kinase (PKAc) with various substrates, nucleotides and cofactors. Importantly, we were able to trap and mimic the initial (Michaelis complex) and final (product complex) stages of the reaction. The results demonstrate that Mg2+, Ca2+, Sr2+, and Ba2+ metal ions bind to the active site and facilitate the reaction to produce ADP and a phosphorylated peptide. The study also revealed that metal-free PKAc can facilitate the phosphoryl transfer reaction; a result that was confirmed with single turnover enzyme kinetics measurements. Comparison of the product and the pseudo-Michaelis complex structures, in conjunction with molecular dynamics simulations, reveals conformational, coordination, and hydrogen bonding changes that help further our understanding of the mechanism, roles of metals, and active site residues involved in PKAc activity.

Biochemical changes accompanying enhanced cardiac contractility by ionophore A23187

1985 ◽  
Vol 249 (6) ◽  
pp. H1204-H1210 ◽  
Author(s):  
J. J. Murray ◽  
P. W. Reed ◽  
J. G. Dobson
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Ionophore A23187 ◽  
Phosphorylase Activity ◽  
Dependent Protein Kinase ◽  
Camp Content ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

We have reported that the divalent cation ionophore A23187, like the beta-adrenergic agonist isoproterenol, increased the force of contraction and rate of relaxation and shortened the duration of contraction of papillary muscles isolated from guinea pigs. A23187 produced a fall in resting tension and decreased the contracture tension of K +/- depolarized muscles, as did isoproterenol. In the present studies, isoproterenol produced a concentration-dependent, rapid, and sustained increase in the cyclic AMP (cAMP) content of papillary muscle. In contrast, A23187 had no detectable effect on cAMP levels, even in the presence of the phosphodiesterase inhibitor, papaverine. Neither drug, at concentrations maximal for contractile effects, altered cyclic GMP (cGMP). Isoproterenol increased the cAMP-dependent protein kinase activity ratio, whereas A23187 did not change the activity of this enzyme. However, both A23187 and isoproterenol produced a concentration-dependent increase in phosphorylase activity. Concentrations of A23187 or isoproterenol that enhanced contractility maximally increased the alkali-labile phosphate (by ca. 35%) but were without effect on the acid-labile, alkali-stable phosphate in the total acid precipitable protein. Contractile effects of isoproterenol, which reflect activated Ca2+ uptake, and the increase in phosphorylase activity produced by this agent are believed to be due to an increase in cAMP with subsequent activation of cAMP-dependent protein kinases and phosphorylation of proteins. A23187 may produce similar contractile effects without an increase in cAMP or cAMP-dependent protein kinase activity by activating other protein kinases and/or inhibiting phosphoprotein phosphatases, most likely by its effects on intracellular calcium.

scholarly journals Vanadium oxoanions and cAMP-dependent protein kinase: an anti-substrate inhibitor

1997 ◽  
Vol 321 (2) ◽  
pp. 333-339 ◽  
Author(s):  
Scott PLUSKEY ◽  
Mohammad MAHROOF-TAHIR ◽  
Debbie C. CRANS ◽  
David S. LAWRENCE
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Competitive Inhibitor ◽  
Serine Threonine Kinase ◽  
Dependent Protein Kinase ◽  
Phosphorylated Proteins ◽  
Camp Dependent Protein Kinase ◽  
Wide Range ◽  
Dependent Protein ◽  
Substrate Inhibitor

Vanadium oxoions have been shown to elicit a wide range of effects in biological systems, including an increase in the quantity of phosphorylated proteins. This response has been attributed to the inhibition of protein phosphatases, the indirect activation of protein kinases via stimulation of enzymes at early steps in signal transduction pathways and/or the direct activation of protein kinases. We have evaluated the latter possibility by exploring the effects of vanadate, decavanadate and vanadyl cation species on the activity of the cAMP-dependent protein kinase (PKA), a serine/threonine kinase. Vanadate, in the form of monomer, dimer, tetramer and pentamer species, neither inhibits nor activates PKA. In marked contrast, decavanadate is a competitive inhibitor (Ki = 1.8ŷ0.1 mM) of kemptide (Leu-Arg-Arg-Ala-Ser-Leu-Gly), a peptide-based substrate. This inhibition pattern is especially surprising, since the negatively charged decavanadate would not be predicted to bind to the region of the active site of the enzyme that accommodates the positively charged kemptide substrate. Our studies suggest that decavanadate can associate with kemptide in solution, which would prevent kemptide from interacting with the enzyme. Vanadium(IV) also inhibits the PKA-catalysed phosphorylation of kemptide, but with an IC50 of 366ŷ10 ƁM. However, in this case V4+ appears to bind to the Mg2+-binding site, since it can substitute for Mg2+. In the absence of Mg2+, the optimal concentration of vanadium(IV) for the PKA-catalysed phosphorylation of kemptide is 100 ƁM, with concentrations above 100 ƁM being markedly inhibitory. However, even at the optimal 100 ƁM V4+ concentration, the Vmax and Km values (for kemptide) are significantly less favourable than those obtained in the presence of 100 ƁM Mg2+. In summary, we have found that oxovanadium ions can directly alter the activity of the serine/threonine-specific PKA.

Cross-activation: overriding cAMP/cGMP selectivities of protein kinases in tissues

1992 ◽  
Vol 70 (12) ◽  
pp. 1283-1289 ◽  
Author(s):  
Hang Jiang ◽  
John B. Shabb ◽  
Jackie D. Corbin
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Cyclic Nucleotide ◽  
The Other ◽  
Dependent Protein Kinase ◽  
Cgmp Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Binding Domains ◽  
Dependent Protein ◽  
Camp And Cgmp

cAMP- and cGMP-dependent protein kinases are homologous proteins and are predicted to exhibit very similar three-dimensional structures. Their cyclic nucleotide binding domains share a high degree of amino acid sequence identity. cAMP- and cGMP-dependent protein kinases are activated relatively specifically by cAMP and cGMP, respectively; and a single alanine–threonine difference between cAMP- and cGMP-binding domains partially accounts for this specificity. Thus, it would be expected that cAMP and cGMP mediate separate physiological effects. However, owing in part to the lack of absolute specificity of either enzyme and to the relatively high level of cAMP or cGMP in certain tissues, it is also possible that either cyclic nucleotide could cross-activate the other kinase. Increases in either cAMP or cGMP cause pig coronary artery relaxation. However, only cGMP-dependent protein kinase specific cyclic nucleotide analogues are very effective in causing relaxation, and cAMP elevation in arteries treated with isoproterenol or forskolin activates cGMP-dependent protein kinase, in addition to cAMP-dependent protein kinase. Conversely, increases in either cAMP or cGMP cause Cl− secretion in T-84 colon carcinoma cells, and the cGMP level in T-84 cells can be elevated sufficiently by bacterial enterotoxin to activate cAMP-dependent protein kinase. These results imply specific regulation of cAMP- and cGMP-dependent protein kinases by the respective cyclic nucleotides, but either cyclic nucleotide is able to cross-activate the other kinase in certain tissues.Key words: cGMP, cAMP, smooth muscle relaxation, protein phosphorylation.

In vitro phosphorylation of ciliary dyneins by protein kinases from Paramecium

1993 ◽  
Vol 106 (4) ◽  
pp. 1369-1376 ◽  
Author(s):  
C.E. Walczak ◽  
D.L. Nelson
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Sucrose Gradient ◽  
Dependent Protein Kinase ◽  
Cgmp Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Ciliary Protein ◽  
Dependent Protein ◽  
Camp And Cgmp

Paramecium dyneins were tested as substrates for phosphorylation by cAMP-dependent protein kinase, cGMP-dependent protein kinase, and two Ca(2+)-dependent protein kinases that were partially purified from Paramecium extracts. Only cAMP-dependent protein kinase caused significant phosphorylation. The major phosphorylated species was a 29 kDa protein that was present in both 22 S and 12 S dyneins; its phosphate-accepting activity peaked with 22 S dynein. In vitro phosphorylation was maximal at five minutes, then decreased. This decrease in phosphorylation was inhibited by the addition of vanadate or NaF. The 29 kDa protein was not phosphorylated by a heterologous cAMP-dependent protein kinase, the bovine catalytic subunit. Phosphorylation of dynein did not change its ATPase activity. In sucrose gradient fractions from the last step of dynein purification, phosphorylation by an endogenous kinase occurred. This phosphorylation could not be attributed to the small amounts of cAMP- and cGMP-dependent protein kinases known to be present, nor was it Ca(2+)-dependent. This previously uncharacterized ciliary protein kinase used casein as an in vitro substrate.

cAMP-dependent protein kinase fromPlasmodium falciparum: an update

Parasitology ◽  
2010 ◽  
Vol 138 (1) ◽  
pp. 1-25 ◽  
Author(s):  
NATHALIE WURTZ ◽  
CHARLES CHAPUS ◽  
JEROME DESPLANS ◽  
DANIEL PARZY
Keyword(s):  
Life Cycle ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Mammalian Cells ◽  
Drug Targets ◽  
Molecular Mechanisms ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Pka Pathway

SUMMARYOne of the most important public health problems in the world today is the emergence and dissemination of drug-resistant malaria parasites.Plasmodium falciparumis the causative agent of the most lethal form of human malaria. New anti-malarial strategies are urgently required, and their design and development require the identification of potential therapeutic targets. However, the molecular mechanisms controlling the life cycle of the malaria parasite are still poorly understood. The published genome sequence ofP. falciparumand previous studies have revealed that several homologues of eukaryotic signalling proteins, such as protein kinases, are relatively conserved. Protein kinases are now widely recognized as important drug targets in protozoan parasites. Cyclic AMP-dependent protein kinase (PKA) is implicated in numerous processes in mammalian cells, and the regulatory mechanisms of the cAMP pathway have been characterized.P. falciparumcAMP-dependent protein kinase plays an important role in the parasite's life cycle and thus represents an attractive target for the development of anti-malarial drugs. In this review, we focus on theP. falciparumcAMP/PKA pathway to provide new insights and an improved understanding of this signalling cascade.

Sign in / Sign up

Export Citation Format

Share Document