The broad objective of this proposal is to elucidate the mechanisms which control the activation of stored maternal mRNAs at fertilization in sea urchin eggs. These RNAs are stored as translationally repressed messenger ribonucleoprotein complexes (mRNPs). A change in intracellular Ca or pH levels or the activation of protein kinase C in some manner alters the structure of the egg mRNPs at fertilization, resulting in their translational activation. The PI proposes to analyze in detail the factors that control the repression and derepression of stored maternal mRNPs. mPNP proteins involved in translation repression will be identified by by comparing the protein patterns of purified inactive and active poly A (+) mRNPs. In addition, mRNP binding proteins will be isolated from in vitro activated egg mRNPs. Antibodies against these mRNP masking factors will be used to monitor changes in mRNP proteins upon mRNP activation at fertilization. Protein kinase C activation or intracellular calcium changes result in the unmasking of egg mRNPs. These changes may activate a cascade of protein phosphorylation reactions. The PI will examine the potential role of phosphorylation in the activation of egg mRNPs both in vivo and in a sea urchin in vitro translation system.
