Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.16.2 (PCP)
 3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphoinositide-specific phospholipase C (PI-PLC) activity in whole homogenates of mouse pancreatic islets decreased 60-85% when the homogenates were incubated at 37 degrees C for 1 h in the presence of down to micromolar concentrations of Ca2+. Ca(2+)-induced inactivation was augmented by calmodulin, the phorbol ester 12-O-tetradecanoylphorbol 13-acetate in the presence of ATP-Mg, and by Mg2+. Inactivation was inhibited when ATP was removed and completely abolished by trifluoperazine and EGTA. Inactivation was not affected by the non-phosphorylating ATP analogue, AMP-PCP, GMP-PNP, glucose, Zn2+ or a series of protease inhibitors. These observations suggest that PI-PLC in broken cell preparations of pancreatic islets may be inactivated via phosphorylation by Ca(2+)-calmodulin-stimulated protein kinase and/or protein kinase C. Inactivation of PI-PLC was reversible. Reactivation started after approx. 2 h incubation, when the concentration of ATP in the homogenate was below 0.15 x 10(-6) M. PI-PLC activity returned to values approx. 25% higher than the initial values. PI-PLC inactivation via phosphorylation by the mentioned protein kinases may constitute a feedback control on the phosphoinositide response, attenuating subsequent diacylglycerol formation and/or Ca2+ mobilization by inositol trisphosphate.
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PMID:Ca(2+)- and ATP-dependent reversible inactivation of pancreatic islet phosphoinositide-specific phospholipase C activity. 166 65

During chondrogenesis in vivo and in vitro, a family of nonhistone proteins (Mr 35,500), designated PCP 35.5, is lost from the nuclei of precartilage mesenchyme cells. A basic subcomponent of this family, designated PCP 35.5b, is phosphorylated during the first few hours of chondrogenesis in vitro by a phosphorylating system whose activity is enhanced 12- to 15-fold by exposure of differentiating precartilage cells to dibutyryl cyclic AMP. This phosphorylating system is present in isolated precartilage cell nuclei, where it retains its dependence on cyclic AMP and its specificity for PCP 35.5b. Assays for nuclear cyclic AMP inhibitable protein phosphatase activity capable of dephosphorylating PCP 35.5b were negative, indicating that the system responsible for phosphorylating this protein is a cyclic AMP-dependent protein kinase. Chromatin fractionation studies indicate that PCP 35.5b is localized at sites previously shown to be closely associated with DNase I-sensitive domains of precartilage cell chromatin. These studies define PCP 35.5b as a strategically located component of precartilage cell chromatin which is the major or sole chromatin target of cyclic AMP-dependent phosphorylation during chondrogenesis. This chromatin modification occurs prior to overt cartilage differentiation and may therefore play a regulatory role in the acquisition of the cartilage cell phenotype.
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PMID:Nuclear events during early chondrogenesis: phosphorylation of the precartilage 35.5-kDa domain-specific chromatin protein and its regulation by cyclic AMP. 302 88

The hypothesis that the ADP-sensitive form of phosphorylated Na+, K+-ATPase contains occluded sodium ions has been tested by a procedure which involves (i) modifying the enzyme with alpha-chymotrypsin or N-ethylmaleimide (NEM) so that the ADP-sensitive form is more stable than it is in the native enzyme, (ii) phosphorylating the modified enzyme with ATP in the presence of labelled sodium ions, and (iii) forcing the phosphorylated enzyme rapidly through a cation-exchange column and measuring the labelled sodium in the effluent. The results show that ADP-sensitive phosphoenzyme prepared from alpha-chymotrypsin- or NEM-modified Na+, K+-ATPase is able to carry labelled sodium ions through a cation-exchange resin. This behaviour was not seen with native Na+, K+-ATPase or when phosphorylation was prevented by the omission of magnesium ions or by the substitution of adenylyl(beta, gamma-methylene)diphosphonate (AMP-PCP) for ATP. The occluded sodium ions were rapidly released when the phosphoenzyme was dephosphorylated by ADP. When alpha-chymotrypsin-modified enzyme was phosphorylated by ATP with 1 mM-sodium in the medium, close to three sodium ions were occluded per phospho group. The stoicheiometry at much lower sodium concentrations could not be determined satisfactorily. A consideration of the rate constants of the reactions thought to be involved in the occlusion of sodium and in the release of sodium from the occluded state shows that, so far as they are known, these constants are compatible with the hypothesis that the occluded-sodium form of the phosphoenzyme plays a central role in sodium transport through the pump.
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PMID:The occlusion of sodium ions within the mammalian sodium-potassium pump: its role in sodium transport. 608 5

Copper sulphate is in use as the molluscicide since six decades. However, the cidal mechanism involved is not understood. Therefore, the effect of copper sulphate added to the ambient medium at a concentration duration strength of 2 ppm X 6 hr, on the particulate fractions of the digestive gland of the pulmonate gastropod snail. Lymnaea luteola has been elucidated. Parameters such as oxidizing capacity, phosphorylating capacity and respiratory control have been studied. P:O and R.C. ratios dropped phenomenally and no uncoupling effect was seen in the presence of PCP in treated snails. These results show that some of the important properties of the particulate preparations have been affected by copperations.
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PMID:Heavy metal ion toxicity in the freshwater gastropod snail host, Lymnaea luteola. 714 19