The broad objective of this proposal is to elucidate the mechanisms that control the activation of protein synthesis at fertilization in sea urchin eggs. The increase in protein synthesis is mediated by both the activation of stored maternal messenger ribonucleoprotein (mRNPs) and an increase in the activity of the translational machinery. Dr. Grainger proposes to do a detailed study of the factors that control the repression and activation of stored maternal mRNPs. Proteins that are involved in the translational repression of egg mRNPs will be identified by comparing the protein pattern of inactive egg poly(A)+mRNPs and active fertilized poly(A)+mRNPs. In addition, potential candidates for masking factors will be isolated from in vitro activated mRNPs. Antibodies against these mRNP masking proteins will be used to monitor changes in mRNP proteins as egg mRNPs become activated at fertilization. Changes in intracellular calcium and pH trigger ugg activation and the increase in the rate of protein synthesis. Dr. Grainger will alter the calcium and pH levels of unfertilized eggs and measure the effect of these changes on the translational activity of egg mRNPs. Using antibodies against the mRNP masking factors, he will determine which proteins are modified or released by these treatments. %%% The unfertilized egg is a metabolically quiescent, non- dividing cell. Fertilization results in the activation of a series of pathways, including those leading to an increase in the rate of protein synthesis. Dr. Grainger proposes to study the biochemical processes involved in this activation of protein synthesis upon fertilization using the sea urchin as a model system.
