A mammalian sperm cytosolic phospholipase C activity generates inositol trisphosphate and causes Ca2+ release in sea urchin egg homogenates.
Injection of sperm extracts triggers Ca2+ oscillations in mammalian eggs similar to those seen at fertilisation. Here, we show that addition of sperm extracts to sea urchin egg homogenates causes Ca2+ release and inositol 1,4,5-trisphosphate (InsP3) production. Furthermore depleting homogenates of phosphatidylinositol lipids using a phosphatidylinositol-specific phospholipase C blocked the sperm extract from causing InsP3 production and a Ca2+ rise. A response could be recovered by the addition of phosphatidylinositol 4,5-bisphosphate to either sperm extracts or egg homogenates. These data indicate that sperm extracts contain an InsP3-generating phospholipase C which may play a role in Ca2+ release at fertilisation.
Jones
K T
KT
Department of Anatomy and Developmental Biology, University College, London, UK. k.jones@ucl.ac.uk
Cruttwell
C
C
Parrington
J
J
Swann
K
K
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology*; D004789:Enzyme Activation; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008297:Male; D009865:Oocytes / Q000201:enzymology; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D012617:Sea Urchins; D013094:Spermatozoa / Q000201:enzymology*; D013552:Swine; D010738:Type C Phospholipases / Q000378:metabolism*
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D015544:Inositol 1,4,5-Trisphosphate; D010738:Type C Phospholipases; D002118:Calcium