Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A monoclonal antibody was prepared against the regulatory subunit (RII) of rat liver type II cAMP-dependent protein kinase. Autophosphorylated and nonphosphorylated RII in extracts from rat liver or hepatocytes were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and quantified by immunoblot analysis with this antibody. Under basal conditions, 90% of hepatocyte RII was in the phosphorylated form. Incubating hepatocytes with 8-bromo-cAMP and a phosphodiesterase inhibitor resulted in activation of cAMP-dependent protein kinase and glycogenolysis but did not affect phospho RII levels. RII phosphorylation was also unaffected by the inclusion of sufficient insulin to cause a decrease in cAMP-dependent protein kinase activity and glycogenolysis. The results indicate that unlike other cell types, dissociation of rat hepatocyte type II cAMP-dependent protein kinase does not result in dephosphorylation of RII. The biochemical basis for the apparent lack of RII dephosphorylation in intact hepatocytes was examined by comparison with smooth muscle where RII is rapidly dephosphorylated. Rat liver extract contained 4-fold less RII and had an 80-fold lower rate of dephosphorylation of endogenous RII compared to bovine smooth muscle extract. The differences in the rates of RII dephosphorylation in tissue extracts were not observed using purified RII from either tissue. These data suggested that the slow rate of RII dephosphorylation in rat hepatocytes is due to a difference in the susceptibility of endogenous rat liver RII to dephosphorylation rather than a difference in phosphatase activity.
Mol Endocrinol 1989 Nov
PMID:Autophosphorylation of rat liver type II cAMP-dependent protein kinase. 255 4

We have evaluated a recently-developed dot-blot hybridization assay for the detection of human rotaviruses using an alkaline-phosphatase conjugated oligonucleotide probe. The lower detection limit of this assay was 1 ng (approximately 5 x 10(7) copies) of the double-stranded (ds) RNA, when a purified preparation from serotype 1 human rotavirus was used but appeared to be much higher when applied on clinical specimens. This assay could detect dsRNA from rotavirus strains belonging to serotypes 1 through 6, 8 and 9. A total of 235 stool specimens were used to evaluate the oligonucleotide probe assay in comparison with polyacrylamide gel electrophoresis and latex agglutination assay (Rotalex). When polyacrylamide gel electrophoresis was used as a gold standard, sensitivity, specificity and positive and negative predictive values of the probe assay were 84, 100, 100 and 89%, respectively. These values were slightly better than those of Rotalex assay which is commonly used in clinical laboratories in Japan. Although the probe assay requires more hands-on time than the immunoassays, the high specificity of this probe assay recommends it as a confirmatory test in the clinical laboratory setting.
Mol Cell Probes 1989 Dec
PMID:Identification of rotaviruses by dot-blot hybridization using an alkaline phosphatase-conjugated synthetic oligonucleotide probe. 255 22

Nuclei from sea urchin blastula embryos synthesize a variety of small RNAs, one of which has identical mobility with sea urchin U1 RNA. This RNA is synthesized by RNA polymerase II and, in a hybridization-selection experiment, was selected by the cloned sea urchin U1 gene. The U1 RNA was initiated with ATP, but not GTP, in isolated nuclei with beta-S- and gamma-S-ribonucleotide triphosphates as substrates. The U1 RNA containing thiophosphate at the 5' end was not capped but accumulated as an uncapped transcript from which the thiophosphate could be removed with calf intestinal phosphatase.
Mol Cell Biol 1985 May
PMID:Synthesis of U1 RNA in isolated nuclei from sea urchin embryos: U1 RNA is initiated at the first nucleotide of the RNA. 258 39

1. Substrates for cAMP-dependent protein kinase were investigated in anterior, intermediate, and neural lobes of the rat pituitary gland. In a cell-free assay system, cAMP increased phosphorylation of 17 K, 33 K, and 60 K macromolecules of the anterior lobe, 17 K, 33 K, 60 K, and 80 K macromolecules of the intermediate lobe, and 60 K, 80 K, and 85 K macromolecules of the neural lobe. 2. Other nucleotides were tested in the intermediate lobe; 8 Br-cAMP mimicked cAMP, cGMP was much less effective than cAMP or 8 Br-cAMP, and 5'-AMP showed no significant effect. The purified catalytic subunit of cAMP-dependent protein kinase evoked the same phosphorylation pattern as the endogenous kinase. 3. Maximum cAMP-dependent phosphorylation occurred at between 1 and 2 min of incubation; after 20 min, phosphorylation was reduced by 80%. This suggests the presence of phosphatase activity in the intermediate lobe. 4. When tested upon dispersed intermediate lobe cells permeabilized by high-voltage electrical discharges, cAMP increased phosphorylation of the 17 K and 33 K macromolecules.
Cell Mol Neurobiol 1988 Mar
PMID:Substrates for adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase in the rat pituitary gland. 284 Oct 26

Human prostatic acid phosphatase (PAcP) has been found to have phosphotyrosyl-protein phosphatase activity (H. C. Li, J. Chernoff, L. B. Chen, and A. Kirschonbaun, Eur. J. Biochem. 138:45-51, 1984; M.-F. Lin and G. M. Clinton, Biochem. J. 235:351-357, 1986) and has been suggested to negatively regulate phosphotyrosine levels, at least in part, by inhibition of tyrosine protein kinase activity (M.-F. Lin and G. M. Clinton, Adv. Protein Phosphatases 4:199-228, 1987; M.-F. Lin, C. L. Lee, and G. M. Clinton, Mol. Cell. Biol. 6:4753-4757, 1986). We investigated the molecular interaction of PAcP with a specific tyrosine kinase, the epidermal growth factor (EGF) receptor, from prostate carcinoma cells. Of several proteins phosphorylated in membrane vesicles from prostate carcinoma cells, PAcP selectively dephosphorylated the EGF receptor. The prostate EGF receptor was more efficiently dephosphorylated by PAcP than by another phosphotyrosyl phosphatase, potato acid phosphatase. Further characterization of the interaction of PAcP with the EGF receptor revealed that the optimal rate of dephosphorylation occurred at neutral rather than at acid pH. Thus, the enzyme that we formerly referred to as PAcP we now call prostatic phosphotyrosyl-protein phosphatase. Hydrolysis of phosphate from tyrosine residues in the immunoprecipitated EGF receptor catalyzed by purified prostatic phosphotyrosyl-protein phosphatase caused a 40 to 50% decrease in the receptor tyrosine kinase activity with angiotensin as the substrate. In contrast, autophosphorylation of the receptor was associated with an increase in tyrosine kinase activity.
Mol Cell Biol 1988 Dec
PMID:The epidermal growth factor receptor from prostate cells is dephosphorylated by a prostate-specific phosphotyrosyl phosphatase. 285 98

The Mr = 33,000 catalytic fragment of rabbit skeletal muscle type 1 protein phosphatase was digested with trypsin after reduction and alkylation. The resulting peptides were isolated, subjected to automated Edman degradation, and their sequences compared to the deduced peptide sequence of the bovine type 2A protein phosphatase cDNA. Of 10 tryptic peptides from the type 1 phosphatase that were sequenced, nine showed a high degree of homology with the type 2A phosphatase. This provides the first direct sequence comparison suggesting that the type 1 and type 2 protein phosphatases, distinguished functionally by their substrate specificities and sensitivity to inhibitors, make up part of a family of closely related gene products with similar structures.
Mol Endocrinol 1987 Oct
PMID:Sequence homologies between type 1 and type 2A protein phosphatases. 285

The effect o 4 weeks dietary administration of the hormone dehydroepiandrosterone (DHEA) on enzyme and morphological phenotype of focal lesions previously induced by dimethylaminoazobenzene (DAB) treatment was investigated in Sprague-Dawley rats. In contrast to the DAB-alone livers where large numbers of glycogen-storing, mixed cell nodules homogeneously positive for glutathione S-transferase P form (GST-P) were apparent, DHEA treated animals were characterized by significantly fewer, more heterogeneous lesions, in some cases demonstrating increased amphophilia and structured basophilia. The enhanced heterogeneity, in some ways reminiscent of that reported earlier for 'reversibility' or 'remodelling' of rapidly induced nodular lesions, was associated with increased catalase (CAT), acid phosphatase (AP) and glucose-6- phosphatase (G6Pase) and decreased glycogen contents and phosphorylase (PHO) activity in both nodules and background parenchyma. Glucose-6-phosphatase (G6PD) activity was elevated irregularly focal lesions also demonstrating a heterogeneous reaction. The experimental data suggest two separate effects of the hormone treatment the first involving modulation of the usual altered phenotype of preneoplastic lesions with a shift towards 'tigroid' cell character and the second, similar to that reported earlier for rapidly induced nodules, involving enhanced phenotypic instability and leading to reduction in numbers.
Virchows Arch B Cell Pathol Incl Mol Pathol 1988
PMID:Modulating influence of dehydroepiandrosterone administration on the morphology and enzyme phenotype of dimethylaminoazobenzene-induced hepatocellular foci and nodules. 290 89

Myosin was purified from chicken brush border cells to greater than 95% homogeneity and in a predominantly non-phosphorylated state. The effects of light chain phosphorylation by a Ca2+-calmodulin-dependent myosin light chain kinase on the conformational, enzymatic and filament assembly properties of this myosin were investigated. The actin-activated MgATPase activity of the non-phosphorylated myosin was low, and upon light chain phosphorylation an eight- to ninefold increase in this activity was observed, which was further potentiated by tropomyosin. Light chain phosphorylation was shown to control the assembly and disassembly of brush border myosin filaments. For example, turbidity measurements and electron microscopy demonstrated that MgATP disassembled non-phosphorylated myosin filaments; the disassembled myosin could reassemble when the light chains were phosphorylated, and could be disassembled again by dephosphorylating the light chains with phosphatase. In the electron microscope, the disassembled non-phosphorylated myosin molecules appeared in a folded conformation, and they were extended when phosphorylated. Proteolytic digestion was used to probe further the conformation of these folded and extended molecules, and their subunit organizations were characterized by a gel overlay technique. Quantitative analysis further demonstrated that light chain phosphorylation alters dramatically the monomer/polymer equilibrium of brush border myosin, shifting it towards filament formation. Comparison of analogous data for myosin from gizzard and thymus shows that each myosin has distinct solubility properties.
J Mol Biol 1986 Apr 05
PMID:Regulation in vitro of brush border myosin by light chain phosphorylation. 294 99

The smooth endoplasmic reticulum (ER) and cytosol fractions of liver homogenates exhibit phosphoprotein phosphatase activity towards glycogen synthase D and phosphorylase a. The following observations suggest that liver contains multiple forms of these phosphatases. Synthase phosphatase activity in either fraction was more readily inactivated by heating than phosphorylase phosphatase activity. Both synthase phosphatase and phosphorylase phosphatase activities in smooth ER were non-competitively inhibited by Mg2+, but were activated by this ion in the cytosol. Synthase phosphatase activities in cytosol and smooth ER were stimulated by a number of sugar phosphates, particularly glucose-1-phosphate, galactose-6-phosphate and fructose-6-phosphate. Erythrose-4-phosphate stimulated synthase phosphatase activity in the cytosol, but inhibited the microsomal enzyme. Phosphorylase phosphatase activities in either fraction were inhibited by most sugar phosphates. Adenosine mono-, di- and tri-phosphates inhibited phosphatase activities in both fractions. Low concentrations of AMP and ADP inhibited phosphorylase phosphatase activities to a greater extent than synthase phosphatase activities. Chromatography of the smooth ER fraction on DEAE-cellulose resulted in the separation of synthase phosphatase from phosphorylase phosphatase, as soluble proteins. The elution profile for the microsomal phosphatase was different from that for the cytosol enzymes. It is concluded that: both synthase phosphatase and phosphorylase phosphatase in liver have at least two isoenzyme forms; synthase phosphatase and phosphorylase phosphatase are separate enzymes; the different behaviour of microsomal and cytosol phosphatases towards divalent cations and sugar phosphates provides a potential mechanism for the differential regulation of these activities in liver.
Mol Cell Biochem 1985 Mar
PMID:Multiple forms of synthase D phosphatase and phosphorylase a phosphatase in liver and regulatory effects of metabolites on their activities. 298 42

The effect of verapamil on sarcolemmal activities of sarcolemmal fragments isolated from aerobically perfused (control) and ischaemic rat hearts was examined. Adding verapamil to the perfusate of aerobically perfused hearts for 75 min enhanced some of the sarcolemmal activities; Na+-K+ ATPase (31%), K+ stimulated phosphatase (31%) and Na+-Ca2+ exchange rate (46%). Adding verapamil directly to the enzymatic incubation media, or to the cardiac homogenate prior to sarcolemmal isolation did not alter these activities, suggesting that these changes are dependent upon addition of verapamil to the intact system. Addition of verapamil to hearts 15 min prior to a 60 min ischaemic episode maintained a number of sarcolemmal activities close to those obtained after aerobic perfusion. Na+-K+ ATPase activity and Na+-Ca2+ exchange received a relative protection while K+ stimulated phosphatase activity was not protected. 5'-nucleotidase activity was completely protected against ischaemia-induced depression. The mechanism whereby verapamil induces these changes in sarcolemmal enzymatic activities is unclear but its ability to maintain these activities at or near normal levels may contribute to its ability to protect against the deleterious effects of ischaemia.
J Mol Cell Cardiol 1985 Jul
PMID:The effect of verapamil on ischaemia-induced changes to the sarcolemma. 299 43


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