Requirement of a Src family kinase for initiating calcium release at fertilization in starfish eggs.

TitleRequirement of a Src family kinase for initiating calcium release at fertilization in starfish eggs.
Publication TypeJournal Article
Year of Publication1999
AuthorsGiusti AF, Carroll DJ, Abassi YA, Terasaki M, Foltz KR, Jaffe LA
JournalJ Biol Chem
Date Published1999 Oct 8
KeywordsAnimals, Calcium, Fertilization, Inositol Phosphates, Microinjections, Mutation, Ovum, Phosphotyrosine, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-fyn, Recombinant Fusion Proteins, Signal Transduction, src Homology Domains, src-Family Kinases, Starfish

Signal transduction leading to calcium release in echinoderm eggs at fertilization requires phospholipase Cgamma-mediated production of inositol trisphosphate (IP(3)), indicating that a tyrosine kinase is a likely upstream regulator. Because previous work has shown a fertilization-dependent association between the Src homology 2 (SH2) domains of phospholipase Cgamma and a Src family kinase, we examined whether a Src family kinase was required for Ca(2+) release at fertilization. To inhibit the function of kinases in this family, we injected starfish eggs with the SH2 domains of Src and Fyn kinases. This inhibited Ca(2+) release in response to fertilization but not in response to injection of IP(3). We further established the specificity of the inhibition by showing that the SH2 domains of several other tyrosine kinases (Abl, Syk, and ZAP-70), and the SH3 domain of Src, were not inhibitory. Also, a point-mutated Src SH2 domain, which has reduced affinity for phosphotyrosine, was a correspondingly less effective inhibitor of fertilization-induced Ca(2+) release. These results indicate that a Src family kinase, by way of its SH2 domain, links sperm-egg interaction to IP(3)-mediated Ca(2+) release at fertilization in starfish eggs.

Alternate JournalJ. Biol. Chem.
PubMed ID10506191