Activation of Src-family PTK activity at fertilization: role of the SH2 domain.
The role of Src-family protein tyrosine kinases (SFKs) in egg activation has been established, in large part, by the observation that GST fusion proteins encoding the SH2 domain of Src or Fyn suppress the sperm-induced calcium transient and cause polyspermy in marine invertebrate eggs. These fusion proteins are thought to act as dominant-negative inhibitors of SFK function; however, the mechanism by which they work is not known. The objective of the present study was to test the hypothesis that fusion proteins containing the above SH2 domains prevent activation of SFKs in response to fertilization. A single cell assay was developed that allows estimation of SFK activity in eggs injected with the GST-Fyn-SH2 fusion protein. The results demonstrate that the GST-Fyn-SH2 fusion protein prevents fertilization induced stimulation of SFK activity at concentrations that also suppress the sperm-induced calcium transient in zebrafish eggs.
Kinsey
William H
WH
Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA. wkinsey@kumc.edu
Wu
W
W
Macgregor
Elinor
E
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004789:Enzyme Activation; D005306:Fertilization / Q000502:physiology*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D008297:Male; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051076:Proto-Oncogene Proteins c-fyn; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D013094:Spermatozoa / Q000378:metabolism; D015027:Zebrafish; D029961:Zebrafish Proteins; D018909:src Homology Domains; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D029961:Zebrafish Proteins; D005982:Glutathione Transferase; D051076:Proto-Oncogene Proteins c-fyn; C494964:fyna protein, zebrafish; D019061:src-Family Kinases; D002118:Calcium