Phospholipid binding properties and functional characterization of a sea urchin phospholipase Cdelta in urchin and mouse eggs.
We recently identified a novel phospholipase Cdelta isoform, PLC-deltasu, in sea urchin gametes, whose precise functional role during fertilization and early embryogenesis remains unknown. Here, we characterized the binding of the PLC-deltasu PH domain to different phosphatidylinositol (PI) phospholipids and studied changes in its localization during fertilization. The PLC-deltasu PH domain bound most strongly to PI(3,4)P(2) and PI(3,5)P(2) phospholipids, in contrast to the PLCdelta1 PH domain which bound predominantly to PI(4,5)P(2). A green fluorescent protein tagged PLC-deltasu PH domain localized to the plasma membrane and its localization increased at fertilization and following addition of a Ca(2+) ionophore. However, recombinant PLC-deltasu failed to cause Ca(2+) signals like those seen at fertilization, in mouse and sea urchin eggs. Our findings suggest that PLC-deltasu is unlikely to be directly involved in the process of egg activation but may play a role in mediating extracellular signals transmitted via the PI 3'-kinase pathway.
Coward
Kevin
K
Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.
Owen
Helen
H
Tunwell
Richard
R
Swann
Karl
K
Parrington
John
J
D000818:Animals; D002478:Cells, Cultured; D047108:Embryonic Development / Q000502:physiology*; D005306:Fertilization / Q000502:physiology*; D007527:Isoenzymes / Q000378:metabolism*; D051379:Mice; D054803:Phospholipase C delta; D010743:Phospholipids / Q000737:chemistry*; D011485:Protein Binding; D012617:Sea Urchins / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism*; D015053:Zygote / Q000378:metabolism*
D007527:Isoenzymes; D010743:Phospholipids; D010738:Type C Phospholipases; D054803:Phospholipase C delta; C518025:Plcd1 protein, mouse