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.

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.

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.

Physiological concentration of atrial natriuretic peptide induces endothelial regeneration in vitro

2003 ◽  
Vol 284 (4) ◽  
pp. H1388-H1397 ◽  
Author(s):  
Hyun Kook ◽  
Hiroshi Itoh ◽  
Bong Seok Choi ◽  
Naoki Sawada ◽  
Kentaro Doi ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Protein Kinase ◽  
Dependent Protein Kinase ◽  
Physiological Concentration ◽  
Cell Numbers ◽  
Cgmp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Regeneration In Vitro

Both nitric oxide (NO) and natriuretic peptides produce apoptosis of vascular smooth muscle cells. However, there is evidence that NO induces endothelial cell proliferation, which suggests that there is a difference in the response of endothelial cells to natriuretic peptides. The purpose of this study was to investigate the effect of atrial natriuretic peptide (ANP) on human endothelial cell survival. ANP within the physiological concentration (10−11mol/l) induced a 52% increase in the number of human coronary arterial endothelial cells and a 63% increase in human umbilical vein endothelial cells at a low concentration of serum. The increase in cell numbers was blocked by pretreatment with RP8-CPT-cGMP (RP8), a cGMP-dependent protein kinase inhibitor, with wortmannin, an Akt/PKB inhibitor, and with PD-98059, an ERK1/2 inhibitor. In a Transwell migration test, ANP also increased the cell migration, and RP8, wortmannin, and PD-98059 blocked this increase. A wound healing assay was performed to examine the effects of ANP on regeneration in vitro. ANP increased both cell numbers and migration, but the effects were blocked by the above three kinase inhibitors. ANP increased the expression of phospho-Akt and of phospho-ERK1/2 within 1.5 h. These results suggest that ANP can potentiate endothelial regeneration by cGMP-dependent protein kinase stimulation and subsequent Akt and ERK1/2 activations.

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.

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