Diacylglycerol production in Xenopus laevis oocytes after microinjection of p21ras proteins is a consequence of activation of phosphatidylcholine metabolism.
Microinjection of p21Ha-ras proteins into Xenopus laevis oocytes induces a rapid increase of 1,2-diacylglycerol (DAG) levels. The observed alterations in DAG levels were consistent with the ability of the protein to induce maturation, measured by germinal vesicle breakdown (GVBD). Both the increase in DAG levels and GVBD activity were dependent on the ability of the proteins to undergo membrane translocation. Alterations of DAG levels or GVBD activity did not correlate with changes in the levels of inositol phosphates. However, at minimal doses sufficient to achieve maximal biological response, a biphasic increase in the amounts of phosphocholine and CDP-choline was observed. The first burst of phosphocholine and CDP-choline preceded the increase in DAG levels. The second peak paralleled the appearance of DAG. Choline kinase activity was also increased in oocyte extracts after p21ras microinjection. These results suggest that both the synthesis and degradation of phosphatidylcholine are activated after microinjection of ras proteins into Xenopus oocytes, resulting in a net production of DAG.
Instituto de Investigaciones Biomedicas, Madrid, Spain.
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Lacal
D000818:Animals; D002797:Choline Kinase / Q000378:metabolism; D003566:Cytidine Diphosphate Choline / Q000378:metabolism; D004075:Diglycerides / Q000096:biosynthesis*; D005989:Glycerides / Q000096:biosynthesis*; D007295:Inositol Phosphates / Q000378:metabolism; D008540:Meiosis; D008845:Microinjections; D015689:Oncogene Protein p21(ras) / Q000008:administration & dosage*; D009865:Oocytes / Q000502:physiology*; D010713:Phosphatidylcholines / Q000378:metabolism*; D014982:Xenopus laevis / Q000502:physiology
D004075:Diglycerides; D005989:Glycerides; D007295:Inositol Phosphates; D010713:Phosphatidylcholines; D003566:Cytidine Diphosphate Choline; D002797:Choline Kinase; D015689:Oncogene Protein p21(ras)