Involvement of protein-tyrosine phosphorylation and dephosphorylation in sperm-induced Xenopus egg activation.
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.
Sato
K
K
Laboratory of Molecular Biology, Biosignal Research Center, Kobe University, Nada, Japan. ksato@inherit.biosig.kobe-u.ac.jp
Iwasaki
T
T
Tamaki
I
I
Aoto
M
M
Tokmakov
A A
AA
Fukami
Y
Y
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
D006131:Growth Inhibitors; D007529:Isoflavones; C004742:daidzein; D019833:Genistein; D011505:Protein-Tyrosine Kinases