Intracellular Cs+ activates the PKA pathway, revealing a fast, reversible, Ca2+-dependent inactivation of L-type Ca2+ current

2003 ◽  
Vol 285 (2) ◽  
pp. C310-C318 ◽  
Author(s):  
Fabien Brette ◽  
Alain Lacampagne ◽  
Laurent Sallé ◽  
Ian Findlay ◽  
Jean-Yves Le Guennec
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitor ◽  
Ventricular Myocytes ◽  
Cyclopiazonic Acid ◽  
Dependent Protein Kinase ◽  
Pipette Solution ◽  
Camp Dependent Protein Kinase ◽  
Dependent Inactivation ◽  
Dependent Protein ◽  
Pka Pathway

Inactivation of the L-type Ca2+ current ( ICaL) was studied in isolated guinea pig ventricular myocytes with different ionic solutions. Under basal conditions, ICaL of 82% of cells infused with Cs+-based intracellular solutions showed enhanced amplitude with multiphasic decay and diastolic depolarization-induced facilitation. The characteristics of ICaL in this population of cells were not due to contamination by other currents or an artifact. These phenomena were reduced by ryanodine, caffeine, cyclopiazonic acid, the protein kinase A inhibitor H-89, and the cAMP-dependent protein kinase inhibitor. Forskolin and isoproterenol increased ICaL by only ∼60% in these cells. Cells infused with either N-methyl-d-glucamine or K+-based intracellular solutions did not show multiphasic decay or facilitation under basal conditions. Isoproterenol increased ICaL by ∼200% in these cells. In conclusion, we show that multiphasic inactivation of ICaL is due to Ca2+-dependent inactivation that is reversible on a time scale of tens of milliseconds. Cs+ seems to activate the cAMP-dependent protein kinase pathway when used as a substitute for K+ in the pipette solution.

scholarly journals ATP mediates both activation and inhibition of K(ATP) channel activity via cAMP-dependent protein kinase in insulin-secreting cell lines.

1989 ◽  
Vol 94 (4) ◽  
pp. 693-717 ◽  
Author(s):  
B Ribalet ◽  
S Ciani ◽  
G T Eddlestone
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitor ◽  
Single Channel ◽  
K Channel ◽  
Channel Activity ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Insulin Secreting Cells ◽  
Dependent Protein ◽  
Inside Out

The single-channel recording technique was employed to investigate the mechanism conferring ATP sensitivity to a metabolite-sensitive K channel in insulin-secreting cells. ATP stimulated channel activity in the 0-10 microM range, but depressed it at higher concentrations. In inside-out patches, addition of the cAMP-dependent protein kinase inhibitor (PKI) reduced channel activity, suggesting that the stimulatory effect of ATP occurs via cAMP-dependent protein kinase-mediated phosphorylation. Raising ATP between 10 and 500 microM in the presence of exogenous PKI progressively reduced the channel activity; it is proposed that this inactivation results from a reduction in kinase activity owing to an ATP-dependent binding of PKI or a protein with similar inhibitory properties to the kinase. A model describing the effects of ATP was developed, incorporating these two separate roles for the nucleotide. Assuming that the efficacy of ATP in controlling the channel activity depends upon the relative concentrations of inhibitor and catalytic subunit associated with the membrane, our model predicts that the channel sensitivity to ATP will vary when the ratio of these two modulators is altered. Based upon this, it is shown that the apparent discrepancy existing between the sensitivity of the channel to low ATP concentrations in the excised patch and the elevated intracellular level of ATP may be explained by postulating a change in the inhibitor/kinase ratio from 1:1 to 3:2 owing to the loss of protein kinase after patch excision. At a low concentration of ATP (10-20 microM), a nonhydrolyzable ATP analogue, AMP-PNP, enhanced the channel activity when present below 10 microM, whereas the analogue blocked the channel activity at higher concentrations. It is postulated that AMP-PNP inhibits the formation of the kinase-inhibitor complex in the former case, and prevents phosphate transfer in the latter. A similar mechanism would explain the interaction between ATP and ADP which is characterized by enhanced activity at low ADP concentrations and blocking at higher concentrations.

Chaperones, somatotroph tumors and the cyclic AMP (cAMP)-dependent protein kinase (PKA) pathway

2020 ◽  
Vol 499 ◽  
pp. 110607 ◽  
Author(s):  
Marie Helene Schernthaner-Reiter ◽  
Giampaolo Trivellin ◽  
Constantine A. Stratakis
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Pka Pathway

The protein kinase A catalytic subunit Cβ2: molecular characterization and distribution of the splice variant

2000 ◽  
Vol 351 (1) ◽  
pp. 123-132 ◽  
Author(s):  
Sandra THULLNER ◽  
Frank GESELLCHEN ◽  
Stefan WIEMANN ◽  
Walter PYERIN ◽  
Volker KINZEL ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Splice Variant ◽  
Cardiac Tissue ◽  
Kinase Inhibitor ◽  
Morphological Changes ◽  
Affinity Purification ◽  
Catalytic Subunit ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

Cβ2, a 46 kDa splice variant of the Cβ isoform, is the largest isoform so far described for catalytic subunits from cAMP-dependent protein kinase in mammals. It differs from Cβ in the first 15 N-terminal residues which are replaced with a 62-residue domain with no similarity to other known proteins. The Cβ2 protein was identified in cardiac tissue by MS, microsequencing and C-subunit-isoform-selective antibodies. The Cβ2 protein has a very low abundance of about 2% of total affinity-purified C subunits from bovine cardiac tissue. This, and the similarity of its biochemical properties to Cα and Cβ, are probably some of the reasons why the Cβ2 protein has escaped detection so far. The abundance of the Cβ2 protein differs dramatically between tissues, with most protein detected in heart, liver and spleen, and the lowest level in testis. Cβ2 protein shows kinase activity against synthetic substrates, and is inhibited by the protein kinase inhibitor peptide PKI(5-24). The degree of Cβ2 removal from tissue extracts by binding to PKI(5-24) depends on the cAMP level, i.e. on the dissociation state of the holoenzyme. Two sites in the protein are phosphorylated: Thr-244 in the activation segment and Ser-385 close to the C-terminus. By affinity purification and immunodetection Cβ2 was found in cattle, pig, rat, mouse and turkey tissue and in HeLa cells. In the cAMP-insensitive CHO 10260 cell line, which has normal Cβ but is depleted of Cα, stable transfection with Cβ2 restored most of the cAMP-induced morphological changes. Cβ2 is a ubiquitously expressed protein with characteristic properties of a cAMP-dependent protein kinase catalytic subunit.

scholarly journals The H89 cAMP-dependent protein kinase inhibitor blocks Plasmodium falciparum development in infected erythrocytes

2001 ◽  
Vol 268 (18) ◽  
pp. 4842-4849 ◽  
Author(s):  
Chiang Syin ◽  
Daniel Parzy ◽  
Francois Traincard ◽  
Irène Boccaccio ◽  
Manju B. Joshi ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Kinase ◽  
Kinase Inhibitor ◽  
Protein Kinase Inhibitor ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein
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