title: Inhibitor of eukaryotic initiation factor 4F activity in unfertilized sea urchin eggs.
abstract: Extracts from unfertilized sea urchin eggs contain an inhibitor of translation that inhibits protein synthesis in cell-free translation systems from sea urchin embryos or rabbit reticulocytes. The inhibitory effects of egg extracts can be reversed by the addition of mammalian eukaryotic initiation factor 4F (eIF-4F) in both sea urchin embryo and reticulocyte systems, suggesting that the inhibitor inactivates this initiation factor. The accumulated data suggest that the ability of eIF-4F to recycle may be compromised. The addition of eIF-4F to cell-free translation systems from unfertilized sea urchin eggs also stimulates protein synthesis. However, the stimulation does not increase protein synthetic activity in the egg cell-free translation system to the levels observed in those produced from 2-hr embryos. This suggests that, although the unfertilized egg contains an inhibitor of eIF-4F and reduced levels of eIF-4F activity, inactivation of this component is only one of the factors involved in the low rate of maternal mRNA utilization found prior to fertilization.
mesh_terms: D000818:Animals; D002474:Cell-Free System; D002970:Cleavage Stage, Ovum / Q000502:physiology; D039562:Eukaryotic Initiation Factor-4F; D005786:Gene Expression Regulation; D010063:Ovum / Q000502:physiology*; D010442:Peptide Chain Initiation, Translational; D010448:Peptide Initiation Factors / Q000037:antagonists & inhibitors*; D012333:RNA, Messenger / Q000502:physiology; D012156:Reticulocytes / Q000502:physiology; D012617:Sea Urchins / Q000196:embryology
chemical_list: D039562:Eukaryotic Initiation Factor-4F; D010448:Peptide Initiation Factors; D012333:RNA, Messenger