Search results for "Transferase"
showing 10 items of 1030 documents
The activity of glutathione S-transferase in hepatopancreas of Procambarus clarkii: Seasonal variations and the influence of environmental pollutants
1991
Abstract 1. 1The glutathione S -transferase activity in hepatopancreas of the American red crayfish Procambarus clarkii after 15 days' acclimatization in tap water aquaria was measured in specimens collected monthly for a whole year, and shows seasonal variation. 2. 2. Previous data on the environmental pollution of Lake Albufera suggest a possible correlation with the activity tested in the different seasons of the year considering the results of non-acclimatized animals.
Effects of N2, O2'-dibutyril cyclic GMP on the nucleoside phosphotransferase activity of the retina of the chick embryos.
1977
In the retina of the chick embryo, 2 different forms of nucleoside phosphotransferase take part in the phosphorylation of thymidine. One is an unstable form with higher molecular weight. The other with lower m. wt is a stable form. This paper shows that N2, O2′-dibutyril cyclic GMP causes a marked decrement of the activity of the unstable nucleoside phosphotransferase.
Gastric histamine methyltransferase: Different methylation rates for enantiomers of side-chain methylated histamine analogues using a highly purified…
1984
The inhibitor/activator and substrate properties of enantiomers of two methylated histamines (MH) were investigated using a histamine methyltransferase preparation which was purified 1207-fold from pig fundic mucosa by ultracentrifugation, ion-exchange chromatography on DEAE-cellulose and preparative electrofocusing. In 1-100 microM concentrations, S-alpha-MH and R-alpha-MH were acceptor substrates as good as histamine itself. When substrate concentrations were increased to 1 mM these substances were methylated to an even greater extent than histamine, since they did not exert substrate inhibition on HMT. Introduction of a further methyl-group into the N alpha-position reduced acceptor subs…
The Non-neuronal Cholinergic System
2001
Acetylcholine, one of the most exemplary neurotransmitters, has been detected in bacteria, algae, protozoa, tubellariae and primitive plants, suggesting an extremely early appearance in the evolutionary process and a wide expression in non-neuronal cells. In plants (Urtica dioica), acetylcholine is involved in the regulation of water resorption and photosynthesis. In humans, acetylcholine and/or the synthesizing enzyme, choline acetyltransferase, have been demonstrated in epithelial (airways, alimentary tract, urogenital tract, epidermis), mesothelial (pleura, pericardium), endothelial, muscle and immune cells (granulocytes, lymphocytes, macrophages, mast cells). The widespread expression o…
Non-neuronal acetylcholine, a locally acting molecule, widely distributed in biological systems: expression and function in humans.
1998
Acetylcholine acts as a neurotransmitter in the central and peripheral nervous systems in humans. However, recent experiments demonstrate a widespread expression of the cholinergic system in non-neuronal cells in humans. The synthesizing enzyme choline acetyltransferase, the signalling molecule acetylcholine, and the respective receptors (nicotinic or muscarinic) are expressed in epithelial cells (human airways, alimentary tract, epidermis). Acetylcholine is also found in mesothelial, endothelial, glial, and circulating blood cells (platelets, mononuclear cells), as well as in alveolar macrophages. The existence of non-neuronal acetylcholine explains the widespread expression of muscarinic …
A role for Rho in receptor- and G protein-stimulated phospholipase C Reduction in phosphatidylinositol 4,5-bisphosphate by Clostridium difficile toxi…
1996
Receptors coupled to heterotrimeric guanine nucleotide-binding proteins (G proteins) activate phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2)-hydrolyzing phospholipase C (PLC) enzymes by activated alpha of free beta gamma subunits of the relevant G proteins. To study whether low molecular weight G proteins of the Rho family are involved in receptor signaling to PLC, we examined the effect of Clostridium difficile toxin B, which glucosylates and thereby inactivates Rho proteins, on the regulation of PLC activity in human embryonic kidney (HEK) cells stably expressing the m3 muscarinic acetylcholine receptor (mAChR) subtype. Toxin B treatment of HEK cells did not affect basal PLC activi…
Rho-mediated activation of PI(4)P5K and lipid second messengers is necessary for promotion of angiogenesis by Semaphorin 4D
2011
Phosphatidylinositol 4-phosphate 5-kinase (PI(4)P5K) is a type I lipid kinase that generates the lipid second messenger phospholipid phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and functions downstream of RhoA in actin organization. It is known to play an essential role in neurite remodeling, yielding a phenotype identical to that seen in cells treated with Semaphorin 4D (Sema4D), a protein that regulates proliferation, adhesion and migration in many different cell types. Plexin-B1, the receptor for Sema4D, activates RhoA in order to generate a pro-angiogenic signal in endothelial cells. Therefore, we looked in human umbilical vein endothelial cells (HUVEC) to determine if Plexin-B1 e…
Control of cellular phosphatidylinositol 4,5-bisphosphate levels by adhesion signals and Rho GTPases in NIH 3T3 fibroblasts
2000
The involvement of small GTPases of the Rho family in the control of phosphoinositide metabolism by adhesion signals was examined in NIH 3T3 fibroblasts. Abrogation of adhesion signals by detachment of cells from their substratum resulted in a time-dependent decrease in the cellular level of PtdIns(4,5)P2 by approximately 50%. This effect could be mimicked by treatment of adherent cells with Clostridium difficile toxin B and toxin B-1470, which inhibit specific subsets of Rho and Ras GTPases. Detachment of cells that had been pretreated with the clostridial toxins did not cause a further reduction in PtdIns(4,5)P2 levels, suggesting that the target GTPases are integrated into the control of…
Role of Redox Signaling, Protein Phosphatases and Histone Acetylation in the Inflammatory Cascade in Acute Pancreatitis: Therapeutic Implications
2010
Acute pancreatitis starts as a local inflammation of the pancreatic tissue but often leads to the systemic inflammatory response syndrome and death by multiple organ failure. Pro-inflammatory cytokines, particularly TNF-alpha and Il-1beta, play a pivotal role together with oxidative stress and glutathione depletion in the inflammatory response in this disease. Most inflammatory mediators act through mitogen activated protein kinases and nuclear factor kB. Nevertheless, elucidation of the precise mechanisms involved in activation and attenuation phases of the inflammatory cascade is still underway. Redox signaling mediated by inactivation of protein phosphatases and histone acetylation trigg…
Gene amplification in fibroblasts from ataxia telangiectasia (AT) patients and in X-ray hypersensitive AT-like Chinese hamster mutants.
2001
In search of functions involved in the regulation of gene amplification, and given the relevance of chromosome breakage in initiating the process, we analyzed the gene amplification ability of cells hypersensitive to inducers of DNA double-strand breaks and defective in cell cycle control: two human fibroblast strains derived from patients affected by ataxia telangiectasia (AT) and two hamster mutant cell lines belonging to complementation group XRCC8 of the rodent X-ray-sensitive mutants. These mutants are considered hamster models of AT cells. To measure gene amplification, the frequency and the rate of occurrence of N-(phosphonacetyl)-L-aspartate resistant cells were determined. In both …