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Involvement of protein‐tyrosine phosphorylation and dephosphorylation in sperm‐induced Xenopus egg activation
Author(s) -
Sato Ken-ichi,
Iwasaki Tetsushi,
Tamaki Ikuo,
Aoto Mamoru,
Tokmakov Alexander A,
Fukami Yasuo
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00123-9
Subject(s) - tyrosine phosphorylation , dephosphorylation , protein tyrosine phosphatase , phosphorylation , tyrosine , biology , tyrosine kinase , sodium orthovanadate , genistein , xenopus , sperm , protein kinase a , phosphatase , protein phosphorylation , microbiology and biotechnology , biochemistry , signal transduction , endocrinology , botany , gene
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.