Biphasic activation of Fyn kinase upon fertilization of the sea urchin egg.
Fertilization results in the tyrosine phosphorylation of several egg proteins within minutes of sperm-egg binding and inhibitor studies have shown that tyrosine kinase activity is required for many aspects of egg activation. The present study demonstrates the presence of p59c-fyn kinase in the sea urchin egg and examines the effect of fertilization on the activity of this enzyme. Fertilization had little effect on Fyn kinase activity during the first 2 min after insemination; however, activity had increased approximately eightfold between 5 and 15 min postinsemination. This initial, rapid increase in kinase activity was followed by a period of slightly elevated kinase activity, which was two- to threefold higher than that in the unfertilized egg. Bindin, as well as various parthenogenic agents known to activate the calcium- and pH-mediated pathways of egg activation, failed to elicit any change in enzyme activity, indicating that activation of the kinase required sperm-induced egg activation. However, phorbol ester treatment did induce a slow increase in kinase activity within 30 to 60 min of administration. These findings indicate that the p59fyn kinase is activated within minutes of fertilization and may play a role in the egg activation process.
Kinsey
W H
WH
Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City 66160, USA.
D000595:Amino Acid Sequence; D000818:Animals; D004527:Egg Proteins / Q000378:metabolism; D004789:Enzyme Activation; D005306:Fertilization; D008969:Molecular Sequence Data; D010063:Ovum / Q000201:enzymology; D010312:Parthenogenesis / Q000187:drug effects; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D012617:Sea Urchins / Q000196:embryology / Q000502:physiology*; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism
D004527:Egg Proteins; D011518:Proto-Oncogene Proteins; D014443:Tyrosine; D051076:Proto-Oncogene Proteins c-fyn; D013755:Tetradecanoylphorbol Acetate