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

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of vasopressin on the toad urinary bladder has been shown to be mediated by cyclic AMP. It has been assumed that, as demonstrated for other systems, this involves activation of cyclic AMP-dependent protein kinase. In order to test this hypothesis we investigated the effect of vasopressin on cyclic AMP-dependent protein kinases in epithelial cells of toad bladders. About 80% of protein kinase activity and cyclic AMP-binding capacity was found to be in the cytosol. DEAE-cellulose chromatography showed a pattern of 15--20% type I and 80--85% type II cyclic AMP-dependent protein kinase. Cytosolic kinase was activated 3--4-fold by cyclic AMP with half-maximal activation at 5 . 10(-8) M. Similarly, half-maximal binding of cyclic AMP occurred at 7 . 10(-8) M. Incubation of toad bladders in Ringer's solution containing 0.1 mM 3-isobutyl-1-methylxanthine, prior to homogenization and assay, showed stable cyclic AMP-binding capacity and protein kinase ratio --cyclic AMP/+cyclic AMP. Exposure of bladders to 10 mU/ml of vasopressin for 10 min caused intracellular activation of protein kinase and decrease in cyclic AMP-binding capacity that were maintained for at least 30 min. Incubation of bladders with increasing concentrations of vasopressin (0.5--100 mU/ml) resulted in a discrepancy between a progressive increase in cyclic AMP levels and a levelling off at 10 mU/ml of vasopressin for the changes in protein kinase ratio and cyclic AMP-binding capacity. The increase in kinase ratio was due to higher activity in the absence of exogenous cyclic AMP and was fully inhibitable by a specific protein kinase inhibitor. Using Sephadex G-25-CM50 column chromatography for separation of holoenzyme and free catalytic subunit we demonstrated that the activation of protein kinase in the vasopressin-treated bladders is due to intracellular dissociation of the kinase. These results show that the effect of vasopressin on the toad bladder involves activation of a cytosolic cyclic AMP-dependent protein kinase. The time course and the dose-response curve of the kinase activation closely parallel vasopressin's effect on osmotic water flow.
...
PMID:Effect of vasopressin on cyclic AMP-dependent protein kinase in toad urinary bladder. 624 97

The components of bovine rod outer segments (ROS) and water-soluble extracts of ROS were separated by SDS-electrophoresis after incubation with [gamma-32P]ATP or [gamma-32P]GTP at different experimental conditions. After that gels were autoradiographed to reveal the phosphorylated intermediates. Our results suggest, that ROS contains the following protein kinase systems: 1) water-soluble cAMP-dependent protein kinases, that uses ATP, but not GTP, and phosphorylates the water-soluble 30 000 molecular weight protein; 2) protein kinase that uses GTP (probably, ATP also) and phosphorylates the 20 000 molecular weight protein in light-adapted ROS; 3) water-soluble cyclic nucleotide- and Ca2+-independent protein kinase that uses ATP rather than GTP and phosphorylates the water-soluble 70 000 molecular weight protein. The concentrations of phosphorylated intermediates in bovine ROS are estimated.
...
PMID:[Phosphorylation of endogenous proteins of bovine retina rod outer segments]. 625 44

Vasopressin stimulates osmotic water flow and urea permeability in the toad urinary bladder via separate cAMP-responsive mechanisms. Hydrazine (10--20 MM), added to the bladder's serosal bath, reversibly enhanced the effect of both low and saturating levels of vasopressin on osmotic water flow, without increasing urea permeability. A small increase in basal water flow was also observed. Cyclic AMP-stimulated water flow was not altered by hydrazine, but hydrazine enhanced the effect of both 8-bromo-cyclic AMP and methylisobutylxantine. Hydrazine increased luminal membrane aggregate frequency in vasopressin-treated tissues examined by freeze-fracture electron microscopy. Hydrazine increased both basal and vasopressin-stimulated adenylate cyclase activity. We could measure no effect of hydrazine on cAMP content; however hydrazine did increase the protein kinase activity ratio (-cAMP/+cAMP) in vasopressin-treated tissues, suggesting that the kinase activity ratio is more sensitive than cAMP content as an index of cAMP-related function in the bladder. Further strengthening the relationship between kinase activation and water flow, we found that methohexital, an inhibitor of vasopressin-stimulated water flow and adenylate cyclase, also decreased the kinase activity ratio in the presence of vasopressin. These studies link closely the role of cAMP-dependent kinase and luminal membrane aggregates to the specific mediation of vasopressin-stimulated water flow in the bladder.
...
PMID:Effect of hydrazine on transport on toad urinary bladder. 625 84

Amrinone is a new noncatechol, nonglycoside agent with cardiotonic and vasodilator properties. This paper examines the effects of amrinone in the toad urinary bladder, a tissue whose function may be altered by many factors which also change cardiovascular activity. Amrinone enhanced the effect of vasopressin and cyclic AMP on water and urea permeabilities, as well as the effect of vasopressin on sodium transport. Consistent with these actions, amrinone inhibited cyclic AMP phosphodiesterase activity in epithelial homogenates and increased both cyclic AMP content and the protein kinase activity ratio measured in intact epithelial cells. The inhibitory effect of amrinone on phosphodiesterase may be relevant to its cardiostimulatory and vasodilator activities.
...
PMID:The effects of amrinone on transport and cyclic AMP metabolism in toad urinary bladder. 625 81

Calcium ion plays a major regulatory role in many hormone-stimulated systems. To determine the site of calcium's action in the toad urinary bladder, we examined the effect of trifluoperazine, a compound that binds specifically to the calcium binding protein, calmodulin, and thereby prevents activation of enzymes by the calcium- calmodulin complex. 10 microM trifluoperazine inhibited vasopressin stimulation of water flow, but did not alter vasopressin's effects on urea permeability or short-circuit current. Trifluoperazine also blocked stimulation of water flow by cyclic AMP and methylisobutylxanthine, implying a "postcyclic AMP" site of action. Consistent with these results, trifluoperazine did not decrease epithelial cyclic AMP content or the cyclic AMP-dependent protein kinase activity ratio. Assay of bladder epithelial supernate demonstrated calmodulin-like activity of 1.5 U/microgram protein. Morphologic studies of vasopressin-treated bladders revealed that trifluoperazine did not alter the volume density of cytoplasmic microtubules or significantly decrease the number of fusions between cytoplasmic, aggregate-containing, elongated vesicles and the luminal membrane. Nonetheless, the frequency of luminal membrane aggregates, structures that correlate well with luminal membrane water permeability, was decreased by greater than 50%. Thus, trifluoperazine appears to inhibit the movement of intramembranous particle aggregates from the fused intracellular membranes to the luminal membrane, perhaps by blocking an effect of calcium on microfilament function.
...
PMID:Effects of trifluoperazine on function and structure of toad urinary bladder. Role of calmodulin vasopressin-stimulation of water permeability. 625 6

The interaction of vasopressin with prostaglandins were examined in the toad bladder by determining water flows, cAMP levels, and cAMP-dependent protein kinase activity. Both water flow and activation of cAMP-kinase in response to vasopressin were enhanced after prostaglandin inhibition, consistent with inhibition of vasopressin-induced cAMP generation by endogenous prostaglandins. On the other hand exogeneous PGE stimulated cAMP generation. PGE1 (10(-7) M) alone did not increase water flow but activated kinase more than vasopressin only. Addition of PGE1 (10(-7) M) and vasopressin inhibited water flow as compared with vasopressin along but increased the kinase ratio above that with vasopressin only. PGE2 (10(-5) M) increased the cAMP content and kinase ratio even more than vasopressin but again resulted in no water flow. Addition of vasopressin and PGE2 (10(-5) M) increased water flow but did not alter cAMP content or the kinase ratio compared with PGE2 alone. Similar results were obtained with PGE1. Accordingly, prostaglandin dissociates cAMP levels and kinase ratio from the hydroosmotic response, suggesting that PGE2 inhibits steps distal to cAMP. Consistent with this, in bladders pretreated with naproxen or meclofenamate, PGE2 (10(-8) to 10(-6) M) inhibited the response to submaximal doses of cAMP (5 mM) or 8-bromo-cAMP (0.03 mM). Furthermore, pretreatment with naproxen significantly enhanced the response to cAMP (5 mM). These studies provide evidence for vasopressin-PGE interaction at the site of cAMP generation and also at a step(s) unrelated to cAMP generation.
...
PMID:Multiple sites for interaction of prostaglandin and vasopressin in toad urinary bladder. 627 15

A role for transmembrane calcium movement in vasopressin stimulation of its target cell has been postulated based on studies with calcium entry blockers such as verapamil. We examined the effect of three sets of structurally different calcium blockers--D600 (an analogue of verapamil), diltiazem, and nifedipine--on water flow in toad bladder. D600 (200 microM), diltiazem (200 microM), and nifedipine (60 microM) inhibited vasopressin-induced water flow but enhanced adenosine 3',5'-cyclic monophosphate (cAMP)-induced water flow, suggesting that the drugs inhibit cAMP generation in response to vasopressin but enhance the response to exogenous cAMP by inhibiting phosphodiesterase activity. In the case of vasopressin stimulation, inhibition of cAMP generation appears to be the overriding effect. This was confirmed by measurements of cAMP content and the protein kinase ratio (-cAMP/+cAMP), which were significantly lower in bladders receiving both D600 and vasopressin than in those receiving vasopressin alone. Furthermore the drugs inhibited activation of adenylate cyclase by vasopressin in cell homogenates and inhibited phosphodiesterase in both homogenates and membrane-free supernatants. Thus these "calcium channel blockers" can directly alter cAMP metabolism in settings where movement of calcium should be irrelevant. The close correlation between the biochemical and transport effects of these agents suggests that their effect on water flow may occur by a direct effect on cellular enzymes or the membranes in which they reside and not by altering local calcium concentrations.
...
PMID:Calcium flow-independent actions of calcium channel blockers in toad urinary bladder. 629 12

Microtubules, microfilaments, and intermediate filaments were found to be associated with the cytoplasmic face of the plasma membrane and even localized on the cell surface following "perturbation" of the plasma membrane. Several hormones interacting with their surface receptors have an effect on the assembly, organization, and orientation of the cytoskeletal system thus inducing changes in cell morphology, motility and aggregation. The cytoskeletal system is probably responsible for the lateral and vertical mobility of plasma membrane receptors and for the efficient coupling of GTP-binding protein to the adenylate cyclase moiety. It is suggested that the cytoskeletal system may be involved in hormone-induced desensitization. The activity of cyclic nucleotide phosphodiesterase and protein kinase is modulated by Ca2+-calmodulin. These enzymes are associated with intermediate filaments and with microtubules which may control their activity and induce nuclear translocation of protein kinase. Stimulation of steroidogenesis by ACTH and LH, enhancement of H2O transport by vasopressin, elevation of the rate of amino acid and glucose transport by insulin, release of pancreatic insulin by glucose, and pituitary hormones by their respective hypothalamic releasing hormones, are only examples of a variety of hormonal responses that may be regulated by the cytoskeletal system. It is obvious that much more experimental study should be done to establish the role of the cytoskeletal system in hormonal action. I do hope this review will stimulate further ideas and experiments which might eventually lead to a better understanding of the role of the cytoskeletal system in the control of adenylate cyclase-cAMP system stimulated by hormones.
...
PMID:Role of cytoskeletal organization in the regulation of adenylate cyclase-cyclic adenosine monophosphate by hormones. 629 17

The interaction of lin-benzoadenosine di- and triphosphates with the catalytic subunit and type II holoenzymes of adenosine cyclic 3',5'-monophosphate (cAMP) dependent protein kinase has been investigated by steady-state kinetics and fluorescence spectroscopy. lin-Benzo-ADP is a competitive inhibitor of the catalytic subunit with respect to ATP with a Ki (8.0 microM) similar to the Ki for ADP (9.0 microM). This value agrees well with the Kd (9.0 microM) determined by fluorescence polarization titration. Type II holoenzymes from bovine brain and skeletal muscle have Kd values for lin-benzo-ADP of 3.4 microM and 3.5 microM, respectively, and each binds approximately 2 mol/mol of R2C2 tetramer. Furthermore, fluorescence polarization studies indicate that both the catalytic subunit and type II holoenzyme bind lin-benzo-ADP rigidly, so that there is little or no rotation of the lin-benzoadenine portion of the molecule within the nucleotide binding site. lin-Benzo-ATP is a substrate for the phosphotransferase activities of protein kinase with peptides, water, or type II regulatory subunit as phosphoryl acceptors. With Leu-Arg-Arg-Ala-Ser-Leu-Gly as phosphoryl acceptor, the Km for lin-benzo-ATP is 11.3 microM, and that for ATP is 11.9 microM. The Vmax with lin-benzo-ATP is 20% of the Vmax with ATP as the substrate [24.9 +/- 1.8 mumol/(min . mg) vs. 5.0 +/- 1.2 mumol/(min . mg)]. Thus lin-benzo-ATP is the best nucleotide substrate (besides ATP) for the catalytic subunit reported. 1,N6-Etheno-ATP (epsilon ATP), on the other hand, is a poor substrate for the catalytic subunit with a Km of 1.8 mM and a Vmax that is 4% of the Vmax for ATP, making it unsuitable as a fluorescence probe for cAMP-dependent protein kinase.
...
PMID:Adenosine cyclic 3',5'-monophosphate dependent protein kinase: interaction of the catalytic subunit and holoenzyme with lin-benzoadenine nucleotides. 630 1

After 2 weeks of goitrogen treatment [propylthiouracil (PTU), 0.02% in drinking water], the thyroids of rats increased to 280% of control wet weight, 270% of dry weight, and 250% of control DNA content. Two phases of growth were apparent, an initial hypertrophy phase lasting 3 days (increase in cell size and gland weight with no detectable increase in DNA) and a hyperplastic phase (increase in DNA with histological evidence of cell proliferation) starting at 3-4 days and continuing through 14 days. The cyclic AMP-dependent protein kinase activity ratio (-cyclic AMP/+cyclic AMP) showed a biphasic pattern during the 2-week thyroid growth period, with maxima at day 1 (132% of control) and day 6 (148% of control). Ornithine decarboxylase (EC 4.1.1.17), the initial enzyme in polyamine biosynthesis, showed a similar biphasic pattern with a 6- to 7-fold elevation in activity at 2-3 days and a 4-fold elevation at 6 days. S-Adenosyl-L-methionine decarboxylase (EC 4.1.1.50), the enzyme which catalyzes spermidine synthesis, was elevated 4-fold at 9 days of treatment. The thyroid total supernatant protein kinase activity (+cyclic AMP) increased to 160% of control by 4 days, returning to control by 14 days of PTU treatment. The thyroid had 10% Type I activity and 90% Type II cyclic AMP-dependent protein kinase activity. The specific activity of both Types I and II remained unchanged for the first 2 days of PTU treatment. Both types increased to 150% of control by 4 days. Type I remained elevated throughout the remainder of the 14 days, in contrast to Type II, which decreased conspicuously to control levels by 6 days. A single injection of thyroid-stimulating hormone (TSH, 1.0 unit/100 g of body weight, i.p.) resulted in a 20-fold increase in thyroid ornithine decarboxylase activity by 4 hr. The same dose of TSH produced only a 3-fold induction of ODC in rats hypophysectomized 2 weeks previously. The thyroid specific activity of Types I and II protein kinase was only 55% and 57% of control, respectively, in these unresponsive rats. Thyroids from rats chronically stimulated for 14 days showed an increase in ornithine decarboxylase following TSH administration similar to that of control rats. Changes in the activation as well as specific activity of Types I and II protein kinase during hypertrophy and hyperplasia underlie the complexity of a cyclic AMP-mediated response.
...
PMID:Alteration in cyclic AMP-dependent protein kinases and polyamine biosynthetic enzymes during hypertrophy and hyperplasia of the thyroid in the rat. 630 31


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---