title: Involvement of protein-tyrosine phosphorylation and dephosphorylation in sperm-induced Xenopus egg activation.
abstract: We have analyzed tyrosine-phosphorylated proteins in Xenopus laevis eggs before and after fertilization by immunoblotting with anti-phosphotyrosine antibody. A number of egg proteins with different subcellular distribution became tyrosine-phosphorylated or dephosphorylated within 30 min after insemination. Tyrosine kinase-specific inhibitors genistein and herbimycin A were found to inhibit sperm-induced egg activation judged by the egg cortical contraction. Surprisingly, sodium orthovanadate, a tyrosine phosphatase inhibitor, also inhibited the egg activation. Moreover, we found that fertilization-dependent tyrosine dephosphorylation of 42-kDa mitogen-activated protein kinase was inhibited in genistein-treated eggs. These results suggest that both protein-tyrosine phosphorylation and dephosphorylation pathways play an important role in the sperm-induced Xenopus egg activation.
authors.affiliation: Laboratory of Molecular Biology, Biosignal Research Center, Kobe University, Nada, Japan. ksato@inherit.biosig.kobe-u.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Sato
authors.forename: T
authors.initials: T
authors.lastname: Iwasaki
authors.forename: I
authors.initials: I
authors.lastname: Tamaki
authors.forename: M
authors.initials: M
authors.lastname: Aoto
authors.forename: A A
authors.initials: AA
authors.lastname: Tokmakov
authors.forename: Y
authors.initials: Y
authors.lastname: Fukami
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005306:Fertilization / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology*; D006131:Growth Inhibitors / Q000494:pharmacology*; D007529:Isoflavones / Q000494:pharmacology*; D008297:Male; D009865:Oocytes / Q000187:drug effects*; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000187:drug effects / Q000378:metabolism; D013084:Sperm-Ovum Interactions / Q000187:drug effects* / Q000502:physiology; D014982:Xenopus laevis
chemical_list: D006131:Growth Inhibitors; D007529:Isoflavones; C004742:daidzein; D019833:Genistein; D011505:Protein-Tyrosine Kinases