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J Cell Biol 1997 Sep 22;1386:1303-11. doi: 10.1083/jcb.138.6.1303.
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Calcium release at fertilization in starfish eggs is mediated by phospholipase Cgamma.

Carroll DJ , Ramarao CS , Mehlmann LM , Roche S , Terasaki M , Jaffe LA .

Although inositol trisphosphate (IP3) functions in releasing Ca2+ in eggs at fertilization, it is not known how fertilization activates the phospholipase C that produces IP3. To distinguish between a role for PLCgamma, which is activated when its two src homology-2 (SH2) domains bind to an activated tyrosine kinase, and PLCbeta, which is activated by a G protein, we injected starfish eggs with a PLCgamma SH2 domain fusion protein that inhibits activation of PLCgamma. In these eggs, Ca2+ release at fertilization was delayed, or with a high concentration of protein and a low concentration of sperm, completely inhibited. The PLCgammaSH2 protein is a specific inhibitor of PLCgamma in the egg, since it did not inhibit PLCbeta activation of Ca2+ release initiated by the serotonin 2c receptor, or activation of Ca2+ release by IP3 injection. Furthermore, injection of a PLCgamma SH2 domain protein mutated at its phosphotyrosine binding site, or the SH2 domains of another protein (the phosphatase SHP2), did not inhibit Ca2+ release at fertilization. These results indicate that during fertilization of starfish eggs, activation of phospholipase Cgamma by an SH2 domain-mediated process stimulates the production of IP3 that causes intracellular Ca2+ release.

PubMed ID: 9298985
PMC ID: PMC2132564
Article link: J Cell Biol

Genes referenced: LOC100888622 LOC100893907 LOC115919910 LOC574936 LOC594349 mmut

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References [+] :
Abassi, Tyrosine phosphorylation of the egg receptor for sperm at fertilization. 1994, Pubmed, Echinobase