Biomaterial Database

CTP:phosphocholine cytidylyltransferase activity in the preimplantation mouse embryo. 1997

E A Moon, and C O'Neill

Department of Physiology, University of Sydney, Royal North Shore Hospital of Sydney, St Leonards, NSW, Australia.

Cytidine 5'-triphosphate (CTP):phosphocholine cytidylyltransferase (EC 2.7.7.15) catalyses the synthesis of the active metabolic intermediate cytidine diphosphocholine (which is mainly used in the synthesis of choline-containing phospholipids). It is a rate-limiting reaction in choline phospholipid biosynthesis in many cells. In this study, a microassay is reported for the detection of this enzyme in small numbers of cells. This enzyme was present in mouse oocytes and at all stages during preimplantation development. Enzyme activity was destroyed by boiling but increased with time and number of embryos in the reaction. Activity in two-cell embryos was dependent on Mg2+ but independent of Ca2+ and was enhanced by the addition of 1 microgram lysophosphatidylethanolamine ml-1 to the reaction mixture. Activity was apparently dependent upon the phosphorylation status of the enzyme since the absence of the phosphatase inhibitor NaF caused a significant inhibition of activity. The enzyme in oocytes had a specific activity of 2.8 +/- 0.3 fmol cytidine diphosphocholine (CDP-choline) per oocyte min-1 (mean +/- SEM). The specific activity in two-cell and eight-cell embryos and blastocysts was not different from that of oocytes. Fertilized one-cell embryos had significantly less activity (1.4 +/- 0.05 fmol CDP-choline produced per embryo min-1) than other stages studied. Furthermore, the enzyme present in one-cell embryos was not capable of being further activated by the addition of exogenous lysophosphatidylethanolamine to the reaction. The increase in activity from the one-cell to the two-cell stage was not inhibited by alpha-amanitin (an inhibitor of RNA polymerase II), cycloheximide (a protein synthesis inhibitor) [1-(5-isoquinolinesulfonyl)-2-methylpiperazine, HCl]dihydrochloride (H-7; a protein kinase inhibitor) and was independent of cell-cycle progression; these results suggest that enzyme activity is independent of transcription, protein synthesis and the action of some kinases, including cell-cycle-dependent kinases. This study provides the first description of cytidylyltransferase in the early mammalian embryo.

UI	MeSH Term	Description	Entries
D008817	Mice, Mutant Strains	Mice bearing mutant genes which are phenotypically expressed in the animals.	Mouse, Mutant Strain,Mutant Mouse Strain,Mutant Strain of Mouse,Mutant Strains of Mice,Mice Mutant Strain,Mice Mutant Strains,Mouse Mutant Strain,Mouse Mutant Strains,Mouse Strain, Mutant,Mouse Strains, Mutant,Mutant Mouse Strains,Mutant Strain Mouse,Mutant Strains Mice,Strain Mouse, Mutant,Strain, Mutant Mouse,Strains Mice, Mutant,Strains, Mutant Mouse
D009713	Nucleotidyltransferases	A class of enzymes that transfers nucleotidyl residues. EC 2.7.7.	Nucleotidyltransferase
D009865	Oocytes	Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).	Ovocytes,Oocyte,Ovocyte
D011493	Protein Kinase C	An serine-threonine protein kinase that requires the presence of physiological concentrations of CALCIUM and membrane PHOSPHOLIPIDS. The additional presence of DIACYLGLYCEROLS markedly increases its sensitivity to both calcium and phospholipids. The sensitivity of the enzyme can also be increased by PHORBOL ESTERS and it is believed that protein kinase C is the receptor protein of tumor-promoting phorbol esters.	Calcium Phospholipid-Dependent Protein Kinase,Calcium-Activated Phospholipid-Dependent Kinase,PKC Serine-Threonine Kinase,Phospholipid-Sensitive Calcium-Dependent Protein Kinase,Protein Kinase M,Calcium Activated Phospholipid Dependent Kinase,Calcium Phospholipid Dependent Protein Kinase,PKC Serine Threonine Kinase,Phospholipid Sensitive Calcium Dependent Protein Kinase,Phospholipid-Dependent Kinase, Calcium-Activated,Serine-Threonine Kinase, PKC
D011500	Protein Synthesis Inhibitors	Compounds which inhibit the synthesis of proteins. They are usually ANTI-BACTERIAL AGENTS or toxins. Mechanism of the action of inhibition includes the interruption of peptide-chain elongation, the blocking the A site of ribosomes, the misreading of the genetic code or the prevention of the attachment of oligosaccharide side chains to glycoproteins.	Protein Synthesis Antagonist,Protein Synthesis Antagonists,Protein Synthesis Inhibitor,Antagonist, Protein Synthesis,Antagonists, Protein Synthesis,Inhibitor, Protein Synthesis,Inhibitors, Protein Synthesis,Synthesis Antagonist, Protein,Synthesis Inhibitor, Protein
D001755	Blastocyst	A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.	Embryo, Preimplantation,Blastocysts,Embryos, Preimplantation,Preimplantation Embryo,Preimplantation Embryos
D002455	Cell Division	The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.	M Phase,Cell Division Phase,Cell Divisions,Division Phase, Cell,Division, Cell,Divisions, Cell,M Phases,Phase, Cell Division,Phase, M,Phases, M
D002855	Chromatography, Thin Layer	Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Chromatography, Thin-Layer,Thin Layer Chromatography,Chromatographies, Thin Layer,Chromatographies, Thin-Layer,Thin Layer Chromatographies,Thin-Layer Chromatographies,Thin-Layer Chromatography
D003513	Cycloheximide	Antibiotic substance isolated from streptomycin-producing strains of Streptomyces griseus. It acts by inhibiting elongation during protein synthesis.	Actidione,Cicloheximide
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme