Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of 8-bromo-cGMP on intracellular calcium concentrations in cultured rat aortic smooth muscle cells were studied. Both angiotensin II and depolarizing concentrations of K+ stimulated Ca2+ accumulation in the cytoplasm. The increase in Ca2+ due to angiotensin II was associated with an increase in inositol phosphates, while that due to K+ was not. Preincubation of cells with 8-bromo-cGMP (100 microM) caused an inhibition of peak Ca2+ accumulation to either angiotensin II or K+. To probe the mechanism of action of cGMP in vascular smooth muscle, the effects of cGMP-dependent protein kinase on Ca2+-ATPase from the cultured cell particulate material were investigated. Ca2+-activated ATPase was stimulated approximately equal to 2-fold by exogenous calmodulin and up to 4-fold by low concentrations of purified cGMP-dependent protein kinase. The inclusion of both calmodulin and cGMP-dependent protein kinase resulted in an additive stimulation of Ca2+-ATPase. Stimulation of Ca2+-ATPase activity was observed at all Ca2+ concentrations tested (0.01-1.0 microM). cAMP-dependent protein kinase catalytic subunit and protein kinase C were either ineffective or less effective than cGMP-dependent protein kinase in stimulating the Ca2+-ATPase from rat aortic smooth muscle cells. These results suggest a possible mechanism of action for cGMP in mediating decreases in cytosolic Ca2+ through activation of a Ca2+-ATPase and the subsequent removal of Ca2+ from the cell.
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PMID:Effects of 8-bromo-cGMP on Ca2+ levels in vascular smooth muscle cells: possible regulation of Ca2+-ATPase by cGMP-dependent protein kinase. 303 2

The amino acid sequence of the Alzheimer disease amyloid precursor (ADAP) has been deduced from the corresponding cDNA, and hydropathy analysis of the sequence suggests a receptor-like structure with a single transmembrane domain. The putative cytoplasmic domain of ADAP contains potential sites for serine and threonine phosphorylation. In the present study, synthetic peptides derived from this domain were used as model substrates for various purified protein kinases. Protein kinase C rapidly catalyzed the phosphorylation of a peptide corresponding to amino acid residues 645-661 of ADAP [ADAP peptide(645-661)] on Ser-655. Ca2+/calmodulin-dependent protein kinase II phosphorylated ADAP peptide (645-661) on Thr-654 and Ser-655. This peptide was virtually ineffective as a substrate for cAMP-dependent protein kinase, cGMP-dependent protein kinase, casein kinase II, or insulin receptor protein-tyrosine kinase. When a homogenate of rat cerebral cortex was used as the source of protein kinase, phosphorylation of ADAP peptide(645-661) was stimulated by calcium/phosphatidylserine/diolein to a level 4.6-fold above the basal level of phosphorylation, consistent with a prominent stimulation by protein kinase C. Using rat cerebral cortex synaptosomes prelabeled with 32Pi, a 32P-labeled phosphoprotein of approximately equal to 135 kDa was immunoprecipitated by using antisera prepared against ADAP peptide(597-624), consistent with the possibility that the holoform of ADAP in rat brain is a phosphoprotein. Based on analogy with the effect of phosphorylation by protein kinase C of juxtamembrane residues in the cytoplasmic domain of the epidermal growth factor receptor and the interleukin 2 receptor, phosphorylation of ADAP may target it for internalization.
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PMID:Phosphorylation of Alzheimer disease amyloid precursor peptide by protein kinase C and Ca2+/calmodulin-dependent protein kinase II. 313 67

We report the molecular cloning of cDNAs for S6 kinase II (S6KII) mRNAs present in Xenopus ovarian tissue. Two cDNAs were isolated by hybridization to oligonucleotide probes designed to encode tryptic peptides isolated from S6KII. The two cDNAs show 91% sequence similarity to each other. These two cDNAs predict proteins of 733 (S6KII alpha) and 629 (S6KII beta) amino acids that show 95% sequence similarity over the 629 amino acids where they are colinear. Amino acids 44-733 of S6KII alpha were expressed in Escherichia coli and the recombinant protein was used to raise antiserum in rabbits. This antiserum reacted with authentic S6KII prepared from Xenopus eggs. This interaction was specifically blocked by the recombinant protein from E. coli. The sequences of S6KII alpha and -beta predict four tryptic peptides whose sequences are identical to four peptides isolated from a tryptic digest of S6KII. The S6KII proteins have a very unusual structure when compared with previously studied protein kinases. They contain two apparent kinase domains, each similar to distinct protein kinases. The amino-terminal 366 amino acids show high sequence similarity to the regions of protein kinase C, the catalytic subunit of cAMP-dependent protein kinase, and cGMP-dependent protein kinase that contain the sites for ATP binding and are believed to be the catalytic centers for phosphotransferase activity. The remainder of the S6 kinase molecule shows high sequence similarity to the ATP-binding and presumed catalytic domain of the catalytic subunit of phosphorylase b kinase.
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PMID:A Xenopus ribosomal protein S6 kinase has two apparent kinase domains that are each similar to distinct protein kinases. 336 49

cAMP-dependent protein kinase, protein kinase C, cGMP-dependent protein kinase, smooth muscle myosin light-chain kinase, and phosphorylase kinase were examined with respect to their ability to phosphorylate porcine atrial muscarinic receptors (mAcChRs). Experiments were performed both in detergent solution and in a reconstituted system containing the mAcChR alone or in the presence of the purified porcine atrial inhibitor guanine nucleotide binding protein (Gi). Only cAMP-dependent protein kinase was capable of phosphorylating the receptor under any of the experimental conditions examined. Phosphorylation of the mAcChR in the detergent-solubilized state resulted in a loss of ligand binding sites that was reversible upon treatment with calcineurin in the presence of calcium and calmodulin. Upon reconstitution, the apparent stoichiometry of phosphorylation was increased by about 15-fold. Carbachol-stimulated covalent incorporation of phosphate was found only in the reconstituted system in the presence of Gi, suggesting that the large agonist-stimulated increase in phosphorylation observed in vivo [Kwatra, M. M., & Hosey, M. M. (1986) J. Biol. Chem. 261, 12429-12432] may in part result from a unique receptor conformation that occurs upon association with this protein. Ligand binding studies indicated that phosphorylation of the mAcChR in the detergent-solubilized or reconstituted state did not affect its interaction with carbachol or L-quinuclidinyl benzilate in vitro. Carbachol-induced stimulation of the GTPase activity of Gi in the reconstituted system was also unaffected by phosphorylation.
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PMID:Phosphorylation of the porcine atrial muscarinic acetylcholine receptor by cyclic AMP dependent protein kinase. 344 51

Three monoclonal antibodies were prepared against rat brain soluble protein kinase C. Two of the antibodies, CKI-97 (IgG2b subclass) and CKII-90 (IgG1 subclass), showed weak binding to native protein kinase C. The third antibody, CKI-33 (IgG2b subclass), showed no binding. However, the mixture of CKI-97, CKII-90, and CKI-33 exhibited much stronger binding activity to this protein kinase than any of the antibodies alone. Although none of these antibodies showed protein kinase C-neutralizing activity, Western blot analysis indicated that these antibodies reacted specifically with protein kinase C, presumably its subspecies, that is present predominantly in nervous tissues. Immunocytochemical studies shows that these antibodies can be used for identification of this enzyme in nervous tissues. In rat Purkinje cells, the immunoreactive material was present throughout the cytoplasm, including dendrites and axons, but was poorly represented in the cell nucleus. In cerebellum, the localization of protein kinase C appears to be very similar to that of cGMP-dependent protein kinase.
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PMID:Monoclonal antibodies against rat brain protein kinase C and their application to immunocytochemistry in nervous tissues. 355 49

Anti-peptide antibodies specific for the neuronal calcium channel alpha 1E subunit (anti-CNE1 and anti-CNE2) were produced to study the biochemical properties and subcellular distribution of the alpha 1E polypeptide from rat brain. Immunoblotting identified a single size form of 245-255 kDa which was a substrate for phosphorylation by cAMP-dependent protein kinase, protein kinase C, cGMP-dependent protein kinase, and calcium/calmodulin-dependent protein kinase II. Ligand-binding studies of alpha 1E indicate that it is not a high affinity receptor for the dihydropyridine isradipine or the peptide toxins omega-conotoxin GVIA or omega-conotoxin MVIIC at concentrations which elicit high affinity binding to other channel types in the same membrane preparation. The alpha 1E subunit is widely distributed in the brain with the most prominent immunocytochemical staining in deep midline structures such as caudate-putamen, thalamus, hypothalamus, amygdala, cerebellum, and a variety of nuclei in the ventral midbrain and brainstem. Staining is primarily in the cell soma but is also prominent in the dendritic field of a discrete subset of neurons including the mitral cells of the olfactory bulb and the distal dendritic branches of the cerebellar Purkinje cells. Our observations indicate that the 245-255 kDa alpha 1E subunit is localized in cell bodies, and in some cases in dendrites, of a broad range of central neurons and is potentially modulated by multiple second messenger-activated protein kinase.
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PMID:Biochemical properties and subcellular distribution of the neuronal class E calcium channel alpha 1 subunit. 747 5

Na+/H+ exchanger (NHE) activity is regulated by several types of receptors directly coupled to distinct classes (i.e. Gs, Gi, Gq, and G12) of heterotrimeric (alpha beta gamma) GTP-binding proteins (G proteins), which, upon activation, modulate production of various second messengers (e.g. cAMP, cGMP, diacylglycerol, inositol trisphosphate, and Ca2+). Recently, four isoforms of the rat Na+/H+ exchanger were identified by molecular cloning. To examine their intrinsic responsiveness to G protein and second messenger stimulation, three of these isoforms, NHE-1, -2, and -3, were stably expressed in mutant Chinese hamster ovary cells devoid of endogenous NHE activity (AP-1 cells). Incubation of cells with either AIF4-, a general agonist of G proteins, or cholera toxin, a selective activator of G alpha s that stimulates adenylate cyclase, accelerated the rates of amiloride-inhibitable 22Na+ influx mediated by NHE-1 and -2, whereas they inhibited that by NHE-3. Similarly, short term treatment with phorbol 12-myristate 13-acetate, which mimics diacylglycerol activation of protein kinase C (PKC), or with agents (i.e. forskolin, 8-(4-chlorophenylthio)-cAMP, and isobutylmethylxanthine) that lead to activation of cAMP-dependent protein kinase (PKA) also stimulated transport by NHE-1 and NHE-2 but depressed that by NHE-3. The effects of phorbol 12-myristate 13-acetate were blocked by depleting cells of PKC or by inhibiting PKC using chelerythrine chloride, confirming a role for PKC in modulating NHE isoform activities. Likewise, the PKA antagonist, H-89, attenuated the effects of elevated cAMPi on NHE-1, -2, and -3, further demonstrating the regulation by PKA. Unlike cAMPi, elevation of cGMPi by treatment with dibutyryl-cGMP or 8-bromo-cGMP had no influence on NHE isoform activities, thereby excluding the possibility of a role for cGMP-dependent protein kinase in these cells. These data support the concept that the NHE isoforms are differentially responsive to agonists of the PKA and PKC pathways.
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PMID:Plasma membrane Na+/H+ exchanger isoforms (NHE-1, -2, and -3) are differentially responsive to second messenger agonists of the protein kinase A and C pathways. 749 49

Na+/Ca2+ exchange contributes to the control of cytosolic free Ca2+ levels ([Ca2+]i) in resting and activated cultured human mesangial cells. We have previously shown that activation of phospholipase C by vasoconstrictors enhances Ca2+ influx upon extracellular Na+ withdrawal. This effect is not mediated by concurrent activation of protein kinase (PK) C, since it occurs even after PKC inhibition, and phorbol esters actually blunt both basal and stimulated Na+/Ca2+ exchange. We now studied the effects of PKA and PKG activation by adenylate/guanylate cyclase stimuli or by permeant analogues of cyclic nucleotides in monolayer cultures loaded with the fluorescent Ca(2+)-sensitive probe, fura-2. The exchanger was inhibited by the stable prostaglandin I2 analogue, iloprost, which is transduced by cAMP (peak [Ca2+]i inhibition by 1 microM iloprost 35 +/- 3%). Similarly, non-receptor activation of adenylate cyclase by 10 microM forskolin inhibited basal and agonist-stimulated Na+/Ca2+ exchange by 52 +/- 4 and 66 +/- 4%, respectively. Dibutyryl-cAMP (0.1 mM) also inhibited stimulated Na(+)-dependent Ca2+ influx by 72 +/- 2%. The particulate guanylate cyclase agonist, atriopeptin III, and the soluble guanylate cyclase activator, glyceryltrinitrate, also inhibited both basal and angiotensin II-stimulated Na+Ca2+ exchange (to a maximum of 53 +/- 5 and 62 +/- 3%, respectively). Dibutyryl-cGMP (1 mM) mimicked the effects of cGMP stimuli, reducing stimulated Na+/Ca2+ exchange by 79 +/- 2%. Therefore, similar to PKC, cyclic nucleotide activation of PKA and PKG regulates Na+/Ca2+ exchange, providing a functional link between transmembrane signalling systems for vasoactive agents in cultured human mesangial cells.
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PMID:Cyclic nucleotides inhibit Na+/Ca2+ exchange in cultured human mesangial cells. 752 69

Endotoxin-associated protein (EP) from Salmonella typhi activated murine resident peritoneal macrophages to produce prostaglandin E2 (PGE2). Cells from both endotoxin nonresponder (C3H/HeJ) and the endotoxin responder (C3H/OuJ) mouse strains were activated by EP. This EP-induced prostaglandin E2 production was blocked by the protein kinase C (PKC) inhibitor H-7 as well as the tyrosine kinase inhibitor genistein, suggesting the involvement of both serine and threonine phosphorylation and tyrosine phosphorylation pathways in the activation of resident peritoneal macrophages by EP. Immunoblot analysis using antiphosphoserine and antiphosphothreonine antibodies showed that EP induced the serine and threonine phosphorylation of a 14-kDa protein (p14). This phosphorylation was not induced by phorbol myristic acid or by lipopolysaccharide endotoxin. Inhibitors of PKC, PKA, and PKG did not block the phosphorylation of p14. However, the tyrosine kinase inhibitor piceatannol blocked p14 serine and threonine phosphorylation, suggesting that this phosphorylation is dependent upon and preceded by a tyrosine phosphorylation step.
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PMID:Induction of serine and threonine protein phosphorylation by endotoxin-associated protein in murine resident peritoneal macrophages. 752 47

Vascular endothelial cells (ECs) are constantly subjected to mechanical strain due to relaxation and contraction of vessel walls. The effects of cyclical strain on endothelin-1 (Et-1) secretion and Et-1 mRNA levels in human umbilical vein ECs were examined. Cultured ECs grown on a flexible membrane base were deformed by negative pressure (16 kPa at 60 cycles/min). Cells subjected to strain showed increased Et-1 secretion (0.54 ng/hr/10(6) cells) compared with unstrained control cells (0.22 ng/hr/10(6) cells). Northern blot analysis of cells strained for 2 hours or longer demonstrated a sustained elevated Et-1 mRNA level at more than double the level in unstrained controls. This strain-induced ET-1 mRNA level returned to its basal level 2 hours after the release of strain. Cells treated with actinomycin D before or during strain treatment showed no strain-induced gene expression. Pretreatment of ECs with a protein kinase C (PKC) inhibitor, Calphostin C, strongly inhibited the strain-induced Et-1 gene expression. Pretreatment of ECs with cAMP- or cGMP-dependent protein kinase inhibitors (KT5720 or KT5823) only partially inhibited the increased Et-1 mRNA levels in strain-treated cells. EGTA strongly inhibited the Et-1 gene expression. The intracellular calcium chelator BAPTA/AM also showed an inhibitory effect on Et-1 mRNA levels. We conclude that mechanical strain can stimulate the secretion of Et-1 from ECs by increasing Et-1 mRNA levels via transcription, and that this gene induction is mediated predominantly via the PKC pathway and requires extracellular Ca2+. This strain-induced Et-1 gene expression in ECs may contribute to the regulation of vascular tone and structure in normal and pathological states of the cardiovascular system.
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PMID:Mechanical strain increases endothelin-1 gene expression via protein kinase C pathway in human endothelial cells. 753 82


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