Two phases of inositol polyphosphate and diacylglycerol production at fertilisation.
[3H]Inositol and [3H]arachidonic acid were used to label polyphosphoinositide phospholipids in sea urchin eggs. Both [3H]inositol polyphosphate (InsP3) and [3H]diacylglycerol (DAG) increase at fertilisation. An early increase in InsP3 occurs as the sperm-induced calcium transient crosses the egg and exocytosis occurs; a later increase in InsP3 as calcium declines and the protein kinase C-dependent Na/H antiporter causes the cytoplasmic pH in increase. These results support suggestions that a calcium-induced hydrolysis of phosphatidylinositol bisphosphate occurs at fertilisation, that the production of diacylglycerol may be essential for exocytosis and that diacylglycerol production at fertilisation stimulates the Na/H antiporter. The increase in [3H]inositol polyphosphate as calcium declines indicates that this second messenger may have some function later in the cell cycle.
Ciapa
B
B
Whitaker
M
M
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002453:Cell Cycle; D004075:Diglycerides / Q000378:metabolism*; D005306:Fertilization; D005989:Glycerides / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism*; D007700:Kinetics; D010063:Ovum / Q000502:physiology*; D012617:Sea Urchins; D013403:Sugar Phosphates / Q000378:metabolism*; D015053:Zygote / Q000502:physiology*
D001095:Arachidonic Acids; D004075:Diglycerides; D005989:Glycerides; D007295:Inositol Phosphates; D013403:Sugar Phosphates; D016718:Arachidonic Acid; D002118:Calcium