Solubilization of the vasopressin receptor from rat liver plasma membranes. Evidence for a receptor X GTP-binding protein complex.

1. Guanosine 5′-[gamma-thio]triphosphate (GTP[S]) stimulated by 50% the rate of release of [3H]choline and [3H]phosphorylcholine in rat liver plasma membranes labelled with [3H]choline. About 70% of the radioactivity released in the presence of GTP[S] was [3H]choline and 30% was [3H]phosphorylcholine. 2. The hydrolysis of phosphorylcholine to choline and the conversion of choline to phosphorylcholine did not contribute to the formation of [3H]choline and [3H]phosphorylcholine respectively. 3. The release of [3H]choline from membranes was inhibited by low concentrations of SDS or Triton X-100. Considerably higher concentrations of the detergents were required to inhibit the release of [3H]phosphorylcholine. 4. Guanosine 5′-[beta gamma-imido]triphosphate and guanosine 5′-[alpha beta-methylene]triphosphate, but not adenosine 5′-[gamma-thio]-triphosphate, stimulated [3H]choline release to the same extent as did GTP[S]. The GTP[S]-stimulated [3H]choline release was inhibited by guanosine 5′-[beta-thio]diphosphate, GDP and GTP but not by GMP. 5. It is concluded that, in rat liver plasma membranes, (a) GTP[S]-stimulated hydrolysis of phosphatidylcholine is catalysed predominantly by phospholipase D with some contribution from phospholipase C, and (b) the stimulation of phosphatidylcholine hydrolysis by GTP[s] occurs via a GTP-binding regulatory protein.

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Effects of Ca2+ and Zn2+ on 5'-nucleotidase activity in rat liver plasma membranes: Hepatic calcium-binding protein (regucalcin) reverses the Ca2+ effect.

Chemical and Pharmaceutical Bulletin ◽

10.1248/cpb.36.321 ◽

1988 ◽

Vol 36 (1) ◽

pp. 321-325 ◽

Cited By ~ 29

Author(s):

MASAYOSHI YAMAGUCHI ◽

SEIICHI MORI

Keyword(s):

Rat Liver ◽

Calcium Binding ◽

Plasma Membranes ◽

Binding Protein ◽

Calcium Binding Protein ◽

Nucleotidase Activity ◽

Liver Plasma Membranes ◽

Rat Liver Plasma Membranes

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The interactions between the activatory guanine nucleotide binding protein and the catalytic subunit of adenylate cyclase in rat liver plasma membranes

Biochemical Journal ◽

10.1042/bj2310039 ◽

1985 ◽

Vol 231 (1) ◽

pp. 39-46 ◽

Cited By ~ 8

Author(s):

S K-F Wong ◽

B R Martin

Keyword(s):

Plasma Membrane ◽

Adenylate Cyclase ◽

Rat Liver ◽

Pertussis Toxin ◽

Plasma Membranes ◽

Binding Protein ◽

Lag Time ◽

Gtp Binding ◽

Rat Liver Plasma Membranes ◽

Maximal Extent

Three GTP-binding proteins of 50 kDa, 45 kDa and 28 kDa were identified by photoaffinity labelling with [gamma-32P]GTP-gamma-azidoanilide (A-GTP) in the rat liver plasma membrane. Pertussis toxin catalysed ADP-ribosylation of a single protein of 40 kDa. A-GTP had no effect on the basal labeling by pertussis toxin. After u.v. irradiation of the membrane in the presence of A-GTP, the GTP-dependent ADP-ribosylation by cholera toxin was increased, while the basal labelling was not affected. These results suggest that A-GTP interacts specifically with the activatory GTP-binding protein (Gs) and does not interact with the inhibitory GTP-binding protein (Gi). The effects of partial photoinactivation of Gs of the rat liver plasma membrane adenylate cyclase system by A-GTP were studied. U.v. irradiation in the presence of increasing concentrations of the analogue caused progressive decrease in the maximal extent of activation by guanosine 5′-[γ-thio]triphosphate, but the Ka was not affected. The rate of activation of liver adenylate cyclase by guanosine 5′-[γ-thio]triphosphate is temperature-dependent. The lag time increased from 0.5 min at 30 degrees C to 2.0-2.5 min at 15 degrees C in the presence of 10 microM-guanosine 5′-[γ-thio]triphosphate. However, Ka remains unaffected by lowering the temperature. Photoinactivation by A-GTP or competitive inhibition by guanosine 5′-[β-thio]diphosphate decreases the maximal extent of activation by guanosine 5′-[γ-thio] triphosphate, but the lag time remains unaffected. The present results support the idea that Gs is tightly associated with the catalytic subunit under basal conditions. The present results also indicate that the transition of an inactive Gs to its active form is the rate-limiting step of the activation of adenylate cyclase by guanosine 5′-[γ-thio]triphosphate in the intact rat liver plasma membranes.

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Partial isolation and characterization of bromosulphophthalein-binding protein from rat liver plasma membranes

Gastroenterologia Japonica ◽

10.1007/bf02774552 ◽

1982 ◽

Vol 17 (2) ◽

pp. 135-143 ◽

Cited By ~ 3

Author(s):

Munehiko Tanno ◽

Hideo Yamada ◽

Toshio Muraki ◽

Noriaki Sekita ◽

Makoto Shimizu ◽

...

Keyword(s):

Rat Liver ◽

Plasma Membranes ◽

Binding Protein ◽

Isolation And Characterization ◽

Liver Plasma Membranes ◽

Rat Liver Plasma Membranes ◽

Partial Isolation

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Effect of guanine nucleotides on polyphosphoinositide synthesis in rat liver plasma membranes

Biochemical Journal ◽

10.1042/bj2710591 ◽

1990 ◽

Vol 271 (3) ◽

pp. 591-597 ◽

Cited By ~ 8

Author(s):

C Benistant ◽

A P Thomas ◽

R Rubin

Keyword(s):

Rat Liver ◽

Plasma Membranes ◽

Atp Hydrolysis ◽

Guanine Nucleotides ◽

The Other ◽

Gtp Binding ◽

Liver Plasma Membranes ◽

Rat Liver Plasma Membranes ◽

Stimulation Of ◽

Rapid Incorporation

The effect of guanosine 5′-[gamma-thio]triphosphate (GTP[S]) on PtdIns and PtdIns(4)P kinase activities was measured in rat liver plasma membranes. The addition of [32P]ATP resulted in the rapid incorporation of 32P into PtdIns(4)P and PtdIns(4,5)P2, with maximal levels reached within 30 s. GTP[S] (25-500 microM) increased the rate and magnitude of [32P]PtdIns(4)P and [32P]PtdIns(4,5)P2 formation by 50 and 120% respectively. Similar stimulatory effects were induced by guanosine 5′-[beta gamma-imido]triphosphate, GTP, GDP and guanosine 5′-[beta-thio]diphosphate. The stimulation of PtdIns phosphorylation by GTP[S] occurred in the presence of 2 mM-EGTA, a condition which fully inhibited phosphoinositide-specific phospholipase C. GTP[S] did not stimulate phosphomonoesterase activity, and its action was not due to the binding of magnesium. However, the overall ATP-hydrolysing activity of the membrane preparation was inhibited by GTP[S] and the other guanine nucleotides. There was a direct correlation between the extent of this inhibition and the stimulation of polyphosphoinositide formation. The results indicate that stimulation of polyphosphoinositide formation by guanine nucleotides in rat liver plasma membranes can be accounted for by an inhibition of ATP hydrolysis. These data are inconsistent with a specific GTP-binding protein (G-protein)-mediated stimulation of PtdIns or PtdIns(4)P kinase.

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