eIF4E association with 4E-BP decreases rapidly following fertilization in sea urchin

The eukaryotic translation initiation factor (eIF) 4F facilitates the recru itment of ribosomes to the mRNA 5' end. The 4E-BPs are small proteins with hypophosphorylated forms that interact with the cap binding protein eIF4E, preventing its interaction with eIF4G, thereby preventing ribosome interact ion with mRNA. In sea urchin, fertilization triggers a rapid rise in protei n synthesis. Here, we demonstrate that a BE-BP homologue exists and is asso ciated with eIF4E in unfertilized eggs. We also show that 4E-BP/eIF4E assoc iation diminishes a few minutes following fertilization. This decrease is c orrelated with a decrease in the total amount of 4E-BP in combination with an increase in the phosphorylation of the protein. We propose that 4E-BP ar ts as a repressor of protein synthesis in unfertilized sea urchin eggs and that 4E-BP/eIF4E dissociation plays an important role in the rise in protei n synthesis that occurs shortly following fertilization. (C) 2001 Academic Press.