Tyrosine phosphorylation of egg proteins: Analysis of its functional role during egg activation

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Cell Biology and Anatomy

First Committee Member

William H. Kinsey - Committee Chair


Fertilization of the sea urchin egg results in the activation of one or more protein tyrosine kinases, and tyrosine phosphorylation of specific egg proteins as well. Using an antibody specific for phosphotyrosine, a group of egg membrane proteins, which serve as in vitro substrates for endogenous tyrosine kinases, were identified and isolated by immunoaffinity chromatography. The tyrosine phosphorylation of a high molecular weight cortex protein (HMWCP) is of particular interest because its phosphorylation correlates temporally with the events of egg activation. Studies on the regulation of HMWCP phosphorylation showed that the fertilization-dependent cytoplasmic pH alkaline shift ensuing from the activation of the Na$\sp+$/H$\sp+$ exchanger stimulates an egg tyrosine kinase and results in phosphorylation of the HMWCP. This event might represent the major step in the signal transduction pathways which lead to the egg activation. An antiserum containing antibodies specific for HMWCP was generated, which would facilitate further characterization of this important substrate protein. The protein tyrosine kinase responsible for the phosphorylation of HMWCP is an abl or abl-related tyrosine kinase based on the immunological evidence. A cDNA fragment was amplified by the polymerase chain reaction using primers which are highly conserved among abl genes from different species, and the amplified cDNA fragment would provide a specific probe for further cloning and sequencing of this abl-related tyrosine kinase gene.


Biology, General; Biology, Molecular; Biology, Cell

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