Biochemical analysis of ecto-nucleotide pyrophosphatase phosphodiesterase activity in brain membranes indicates involvement of NPP1 isoenzyme in extracellular hydrolysis of diadenosine polyphosphates in central nervous system☆

2007 ◽  
Vol 50 (4) ◽  
pp. 581-590 ◽  
Author(s):  
A ASENSIO ◽  
C RODRIGUEZFERRER ◽  
A CASTANEYRAPERDOMO ◽  
S OAKNIN ◽  
P ROTLLAN
Author(s):  
Jesús Pintor ◽  
Charles H. V. Hoyle ◽  
Javier Gualix ◽  
M. Teresa Miras-Portugal

1984 ◽  
Vol 221 (2) ◽  
pp. 361-368 ◽  
Author(s):  
J M Bradbury ◽  
R J Thompson

Endogenous cyclic AMP-stimulated phosphorylation of a 49700-Mr Wolfgram protein component in rabbit central nervous system was investigated by using photoaffinity labelling and 2′,3′-cyclic nucleotide 3′-phosphodiesterase activity staining after electroblotting on to nitrocellulose paper. Photoaffinity labelling with 8′-azidoadenosine 3′,5′-cyclic monophosphate showed a cyclic AMP-binding protein that appeared to be intrinsic to the myelin membrane and appeared to represent the R-subunit of a type I cyclic AMP-dependent protein kinase. This photoaffinity-labelled protein was of larger apparent Mr than the protein showing cyclic AMP-stimulated phosphorylation. Blotting of one-dimensional sodium dodecyl sulphate/polyacrylamide-gel electrophoretograms followed by staining for 2′,3′-cyclic nucleotide 3′-phosphodiesterase activity showed two activity bands corresponding to the two components of the Wolfgram protein doublet. Cyclic AMP-stimulated protein phosphorylation corresponded to the upper component of this doublet. Electroblotting of two-dimensional non-equilibrium pH-gradient electrophoretograms also showed co-migration of cyclic AMP-stimulated protein phosphorylation with enzyme activity. It is proposed that central-nervous-system myelin contains an endogenous type I cyclic-AMP dependent protein kinase that phosphorylates the larger subunit of 2′,3′-cyclic nucleotide 3′-phosphodiesterase.


1996 ◽  
Vol 49 (4) ◽  
pp. 443 ◽  
Author(s):  
GB Barlin ◽  
LP Davies ◽  
SJ Ireland

Some 6-arylthio( aryloxy and alkylthio )-3-( acetamidomethyl , benzamidomethyl, methoxy and unsubstituted )-2-arylimidazo[1,2-b] pyridazines have been prepared and examined for their ability to displace [3H]diazepam from rat brain membranes. The most active compound was 3-acetamidomethyl-2-(3',4'-methylenedioxyphenyl)-6-phenylthioimidazo[1,2-b] pyridazine with IC50 4.4 nM. The 3-acylaminomethyl-6-(2- and 3-methoxyphenylthio)-2-phenylimidazo[1,2-b] pyridazines proved less active than their 6-phenylthio analogues, and larger substituents at the 2- and 6-positions markedly decreased binding. Significant differences in binding ability have been observed between 3-acylaminomethyl-2-aryl-6-phenylthioimidazo[1,2-b] pyridazines and the corresponding imidazo [1,2-a]pyridines.


1965 ◽  
Vol 43 (3) ◽  
pp. 441-454
Author(s):  
J. E. TREHERNE ◽  
D. S. SMITH

1. A very rapid metabolism of 3H-labelled acetylcholine has been demonstrated in the intact abdominal nerve cord. It has been shown that the cholinesterase system is effective in drastically reducing the concentration of acetylcholine in the extracellular fluid of the terminal abdominal ganglion with bathing solutions of up to IO-2M acetylcholine. 2. Evidence has been obtained which indicates that an appreciable hydrolysis of acetylcholine occurs at the periphery of the nerve cord. This effect is correlated with the electronmicroscopic demonstration of regions of eserine-sensitive cholinesterase located on glial membranes in the periphery of ganglia and connectives. It is suggested that some hydrolysis of extraneous acetylcholine may occur in the fibrous layer of the nerve sheath as a result of an accumulation of diffusible acetylcholinesterase in this region. 3. The results are discussed in relation to the possible involvement of the conventional cholinergic system in synaptic transmission in the central nervous system of this insect.


1977 ◽  
Vol 130 (2) ◽  
pp. 299-313 ◽  
Author(s):  
George R. Uhl ◽  
James P. Bennett ◽  
Solomon H. Snyder

1990 ◽  
Vol 68 (4) ◽  
pp. 800-803 ◽  
Author(s):  
Frederick B. St.C. Palmer

The activities and subcellular distributions of the hydrolases that degrade polyphosphoinositides were compared in the developing chick central nervous system. Specific activities increased 2- 3-fold and total activities increased 13-to 16-fold. Phosphatidylinositol 4-phosphate phosphatase is localized in membranes (78%), but is preferentially associated with nonmyelin membranes, since the increase in specific activity preceded myelination and proportions of membrane and soluble activities were constant during accumulation of myelin membranes. Phosphatidylinositol 4,5-bisphosphate phosphatase is largely soluble in embryonic (57%) and myelinated brain (50%). Although specific activity increased coincident with myelination, approximately equal increases in soluble and membrane activity indicate no preferential association with myelin membranes. Phosphatidylinositol 4,5-bisphosphate phosphodiesterase activity increased only in the early stages of myelination, but showed some preferential association with myelin membranes, since the proportion of soluble diesterase declined from 40 to 25%.Key words: brain, development, myelin, phosphodiesterase, phosphoinositide, phosphomonoesterase, phospholipids.


1994 ◽  
Vol 47 (11) ◽  
pp. 2001 ◽  
Author(s):  
GB Barlin ◽  
LP Davies ◽  
RA Davis ◽  
PW Harrison

Syntheses are reported for 6-( methylthio, ethylthio, propylthio, substituted benzylthio and chloro )-3-( methoxy, unsubstituted and benzamidomethyl )-2-arylimidazo[1,2-b] pyridazines containing methoxy, methylenedioxy and methyl groups attached to phenyl substituents . In tests of the ability of these compounds to displace [3H]diazepam from rat brain membranes, 3-methoxy-6-(3′,4′-methylenedioxybenzylthio)-2- (3′,4′-methylenedioxyphenyl) imidazo [1,2-b] pyridazine (IC50 1 nM) bound most strongly; methylenedioxy groups were beneficial to activity whereas polymethoxy or dimethyl substituents were generally detrimental.


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