scholarly journals Role of phosphatidylinositide metabolism in ras-induced Xenopus oocyte maturation.

1990 ◽  
Vol 10 (3) ◽  
pp. 923-929 ◽  
Author(s):  
B T Pan ◽  
G M Cooper
Keyword(s):  
Xenopus Oocytes ◽  
Second Messengers ◽  
Phospholipid Metabolism ◽  
Meiotic Maturation ◽  
Ras Oncogene ◽  
Ras Protein ◽  
32P Incorporation ◽  
Kinetics Of ◽  
Oncogene Protein

Microinjection of Xenopus oocytes with ras protein (p21) was used to investigate the role of phospholipid metabolism in ras-induced meiotic maturation. Induction of meiosis by ras was compared with induction by progesterone, insulin, and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Neomycin, which specifically binds to phosphatidylinositides and inhibits their metabolism, blocked meiotic maturation induced by ras or insulin but not by progesterone or TPA. In addition, p21 and TPA, but not insulin or progesterone, stimulated the incorporation of 32Pi into oocyte lipids. ras protein specifically stimulated 32P incorporation into phosphatidylinositides, whereas both ras and TPA stimulated 32P incorporation into phosphatidylcholine and phosphatidylethanolamine. The stimulatory effect of p21 on phosphatidylinositide metabolism correlated with the dose response and kinetics of ras-induced meiotic maturation. In addition, the ras oncogene protein was more potent than the proto-oncogene protein both in inducing meiotic maturation and in stimulating phosphatidylinositide metabolism. These results indicate that phosphatidylinositide turnover is required for ras-induced meiosis and suggest that phosphatidylinositide-derived second messengers mediate the biological activity of ras in Xenopus oocytes.

Role of phosphatidylinositide metabolism in ras-induced Xenopus oocyte maturation

1990 ◽  
Vol 10 (3) ◽  
pp. 923-929
Author(s):  
B T Pan ◽  
G M Cooper
Keyword(s):  
Xenopus Oocytes ◽  
Second Messengers ◽  
Phospholipid Metabolism ◽  
Meiotic Maturation ◽  
Ras Oncogene ◽  
Ras Protein ◽  
32P Incorporation ◽  
Kinetics Of ◽  
Oncogene Protein

Microinjection of Xenopus oocytes with ras protein (p21) was used to investigate the role of phospholipid metabolism in ras-induced meiotic maturation. Induction of meiosis by ras was compared with induction by progesterone, insulin, and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Neomycin, which specifically binds to phosphatidylinositides and inhibits their metabolism, blocked meiotic maturation induced by ras or insulin but not by progesterone or TPA. In addition, p21 and TPA, but not insulin or progesterone, stimulated the incorporation of 32Pi into oocyte lipids. ras protein specifically stimulated 32P incorporation into phosphatidylinositides, whereas both ras and TPA stimulated 32P incorporation into phosphatidylcholine and phosphatidylethanolamine. The stimulatory effect of p21 on phosphatidylinositide metabolism correlated with the dose response and kinetics of ras-induced meiotic maturation. In addition, the ras oncogene protein was more potent than the proto-oncogene protein both in inducing meiotic maturation and in stimulating phosphatidylinositide metabolism. These results indicate that phosphatidylinositide turnover is required for ras-induced meiosis and suggest that phosphatidylinositide-derived second messengers mediate the biological activity of ras in Xenopus oocytes.

Internal pH of Xenopus oocytes: A study of the mechanism and role of pH changes during meiotic maturation

1983 ◽  
Vol 100 (1) ◽  
pp. 133-146 ◽  
Author(s):  
Michael F. Cicirelli ◽  
Kenneth R. Robinson ◽  
L.Dennis Smith
Keyword(s):  
Xenopus Oocytes ◽  
Meiotic Maturation ◽  
Ph Changes ◽  
Internal Ph

scholarly journals Equilibria between conformational states of the Ras oncogene protein revealed by high pressure crystallography

2022 ◽  
Author(s):  
Eric Girard ◽  
Rui P Lopes ◽  
Michael Spoerner ◽  
Anne-Claire Dhaussy ◽  
Thierry Prangé ◽  
...  
Keyword(s):  
High Pressure ◽  
Small Gtpase ◽  
Ras Oncogene ◽  
Conformational States ◽  
Ras Protein ◽  
Allosteric Transitions ◽  
High Pressure Crystallography ◽  
Oncogene Protein

In this work, we experimentally investigate the allosteric transitions between conformational states on the Ras oncogene protein using high pressure crystallography. Ras protein is a small GTPase involved in central...

scholarly journals H-ras(val12) induces cytoplasmic but not nuclear events of the cell cycle in small Xenopus oocytes.

1990 ◽  
Vol 1 (7) ◽  
pp. 543-554 ◽  
Author(s):  
A D Johnson ◽  
R J Cork ◽  
M A Williams ◽  
K R Robinson ◽  
L D Smith
Keyword(s):  
Xenopus Oocytes ◽  
Meiotic Maturation ◽  
Cortical Granule ◽  
Ras Protein ◽  
Oncogenic Ras ◽  
Endogenous Protein ◽  
Stage 4 ◽  
Nuclear Events ◽  
Activation Response ◽  
Vitelline Envelope

Microinjection of H-ras(val12) protein into fully grown Xenopus oocytes has been shown to induce meiotic maturation. In the present study, mRNA encoding the mutant ras protein was injected into both fully grown (stage 6) and growing (stage 4) oocytes. The mRNA induced nuclear breakdown in stage 6 oocytes, as expected. However, the mRNA induced neither nuclear breakdown nor maturation promoting factor when injected into stage 4 oocytes. Instead, the response in stage 4 oocytes included an activation pulse of calcium, cortical granule breakdown, elevation of the vitelline envelope, and abortive cleavage furrows, all of which are characteristics of the activation response in mature eggs. In addition, the injected mRNA led to increased rates of endogenous protein synthesis and the migration of subcortical organelles into the oocyte interior. These observations are discussed relative to the suggestion that oncogenic ras protein leads to an increase in both diacylglycerol and inositol trisphosphate, which then regulate the various cytoplasmic events described.

Thermodynamic and Kinetic Investigation of the Solvent Effect on the Oxidation of [Co(en)2SCH2COO]+ with S2O82- In Water-Methanol and Water-tert-Butyl Alcohol Mixtures

1993 ◽  
Vol 58 (5) ◽  
pp. 1001-1006 ◽  
Author(s):  
Oľga Vollárová ◽  
Ján Benko
Keyword(s):  
Transfer Functions ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Oxidation Of Co ◽  
Kinetics Of Oxidation ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Alcohol Mixtures ◽  
Kinetics Of

The kinetics of oxidation of [Co(en)2SCH2COO]+ with S2O82- was studied in water-methanol and water-tert-butyl alcohol mixtures. Changes in the reaction activation parameters ∆H≠ and ∆S≠ with varying concentration of the co-solvent depend on the kind of the latter, which points to a significant role of salvation effects. The solvation effect on the reaction is discussed based on a comparison of the transfer functions ∆Ht0, ∆St0 and ∆Gt0 for the initial and transition states with the changes in the activation parameters accompanying changes in the CO-solvent concentration. The transfer enthalpies of the reactant were obtained from calorimetric measurements.

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