scholarly journals Epoxyeicosatrienoic acid stimulates ADP-ribosylation of a 52 kDa protein in rat liver cytosol

1992 ◽  
Vol 281 (1) ◽  
pp. 185-190 ◽  
Author(s):  
K Seki ◽  
A Hirai ◽  
M Noda ◽  
Y Tamura ◽  
I Kato ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Rat Liver ◽  
Epoxyeicosatrienoic Acid ◽  
Liver Cytosol ◽  
Adp Ribosylation ◽  
A Subunit ◽  
Gs Alpha ◽  
Adp Ribosyltransferase ◽  
Rat Liver Cytosol

In rat liver cytosol, rapid ADP-ribosylation of a 52 kDa protein by endogenous ADP-ribosyltransferase(s) was observed. This ADP-ribosylation was stimulated dose-dependently by 14,15-epoxyeicosatrienoic acid (14,15-EET), one of the metabolites of arachidonic acid by NADPH-dependent cytochrome P-450 mono-oxygenase. This stimulatory effect required the presence of GTP or its non-hydrolysable analogues, guanosine 5′-[beta gamma-imido]triphosphate or guanosine 5′-[gamma-thio]triphosphate. Of four regioisomeric EETs, 14,15-EET was the most potent. No stimulatory effect was observed with addition of 14,15-dihydroxyeicosatrienoic acid, a stable metabolite of 14,15-EET. The 52 kDa protein was not ADP-ribosylated by cholera toxin A subunit and pertussis toxin, and was not recognized by anti-Gs alpha and anti-Gi alpha antibodies. However, the 52 kDa protein could be photoaffinity-labelled with 8-azidoguanosine 5′-[alpha-32P]triphosphate. These results suggest that the 52 kDa protein is neither Gs nor Gi, though it may have a GTP-binding site. These results contribute to the understanding of the role of mono-oxygenase metabolites of arachidonic acid in intracellular signal transduction.

scholarly journals Activation and inactivation of phosphoenolpyruvate carboxykinase by ferrous ions

1980 ◽  
Vol 185 (2) ◽  
pp. 451-454 ◽  
Author(s):  
C H Reynolds
Keyword(s):  
Rat Liver ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Protein Fractions ◽  
Time Dependent ◽  
Ferrous Ions ◽  
Irreversible Loss ◽  
Liver Cytosol ◽  
Rat Liver Cytosol

Phosphoenolpyruvate carboxykinase from rat liver cytosol is activated by Fe2+ ions in either direction of catalysis. Preincubation of the purified enzyme with Fe2+ ions causes a time-dependent irreversible loss of activity; this is not seen with unpurified enzyme. Purified enzyme can be protected from inactivation by Fe2+ ions by partially purified protein fractions from liver (ferroactivator fractions). The possible role of ferroactivator and Fe2+ ions in regulating phosphoenolpyruvate carboxykinase is discussed.

scholarly journals Purification and characterization of rat liver minoxidil sulphotransferase

1990 ◽  
Vol 270 (3) ◽  
pp. 721-728 ◽  
Author(s):  
S J Hirshey ◽  
C N Falany
Keyword(s):  
Molecular Mass ◽  
Rat Liver ◽  
Substrate Inhibition ◽  
Active Form ◽  
Structural Similarity ◽  
Liver Cytosol ◽  
Low Concentrations ◽  
Exclusion Chromatography ◽  
A Subunit ◽  
Rat Liver Cytosol

Minoxidil (Mx), a pyrimidine N-oxide, is used therapeutically as an antihypertensive agent and to induce hair growth in patients with male pattern baldness. Mx NO-sulphate has been implicated as the agent active in producing these effects. This paper describes the purification of a unique sulphotransferase (ST) from rat liver cytosol that is capable of catalysing the sulphation of Mx. By using DEAE-Sepharose CL-6B chromatography, hydroxyapatite chromatography and ATP-agarose affinity chromatography, Mx-ST activity was purified 240-fold compared with the activity in cytosol. The purified enzyme was also capable of sulphating p-nitrophenol (PNP) at low concentrations (less than 10 microM). Mx-ST was purified to homogeneity, as evaluated by SDS/PAGE and reverse-phase h.p.l.c. The active form of the enzyme had a molecular mass of 66,000-68,000 Da as estimated by gel exclusion chromatography and a subunit molecular mass of 35,000 Da. The apparent Km values for Mx, 3′-phosphoadenosine 5′-phosphosulphate and PNP were 625 microM, 5.0 microM and 0.5 microM respectively. However, PNP displayed potent substrate inhibition at concentrations above 1.2 microM. Antibodies raised in rabbits to the pure enzyme detected a single band in rat liver cytosol with a subunit molecular mass of 35,000 Da, as determined by immunoblotting. The anti-(rat Mx-ST) antibodies also reacted with the phenol-sulphating form of human liver phenol sulphotransferase, suggesting some structural similarity between these proteins.

scholarly journals Alterations in translatable messenger RNA coding for phosphoenolpyruvate carboxykinase (GTP) in rat liver cytosol during deinduction.

1978 ◽  
Vol 253 (12) ◽  
pp. 4327-4332
Author(s):  
D. Kioussis ◽  
L. Reshef ◽  
H. Cohen ◽  
S.M. Tilghman ◽  
P.B. Iynedjian ◽  
...  
Keyword(s):  
Rat Liver ◽  
Messenger Rna ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Liver Cytosol ◽  
Rat Liver Cytosol

scholarly journals Transformation of the glucocorticoid receptor in rat liver cytosol by lysosomal enzymes.

1979 ◽  
Vol 254 (5) ◽  
pp. 1537-1539 ◽  
Author(s):  
J. Carlstedt-Duke ◽  
O. Wrange ◽  
E. Dahlberg ◽  
J.A. Gustafsson ◽  
B. Högberg
Keyword(s):  
Glucocorticoid Receptor ◽  
Rat Liver ◽  
Lysosomal Enzymes ◽  
Liver Cytosol ◽  
Rat Liver Cytosol
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