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Different Ca2+-releasing abilities of sperm extracts compared with tissue extracts and phospholipase C isoforms in sea urchin egg homogenate and mouse eggs

Lookup NU author(s): Professor Keith Jones


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A soluble phospholipase C (PLC) from boar sperm generates InsP(3) and hence causes Ca2+ release when added to sea urchin egg homogenate. This PLC activity is associated with the ability of sperm extracts to cause Ca2+ oscillations in mammalian eggs following fractionation. A sperm PLC may, therefore, be responsible for causing the observed Ca2+ oscillations at fertilization. In the present study we have further characterized this boar sperm PLC activity using sea urchin egg homogenate. Consistent with a sperm PLC acting on egg PtdIns(4,5)P-2, the ability of sperm extracts to release Ca2+ was blocked by preincubation with the PLC inhibitor U73122 or by the addition of neomycin to the homogenate. The Ca2+-releasing activity was also detectable in sperm from other species and in whole testis extracts. However, activity was not observed in extracts from other tissues. Moreover recombinant PLC beta 1, -gamma 1, -gamma 2, -delta 1, all of which had higher specific activities than boar sperm extracts, were not able to release Ca2+ in the sea urchin egg homogenate. In addition these PLCs were not able to cause Ca2+ oscillations following microinjection into mouse eggs. These results imply that the sperm PLC possesses distinct properties that allow it to hydrolyse PtdIns(4,5)P-2 in eggs.

Publication metadata

Author(s): Jones KT; Matsuda M; Parrington J; Katan M; Swann K

Publication type: Article

Publication status: Published

Journal: Biochemical Journal

Year: 2000

Volume: 346

Issue: 3

Pages: 743-749

ISSN (print): 0264-6021

ISSN (electronic): 1470-8728

Publisher: Portland Press