Modifications to the translational apparatus which affect the regulation of protein synthesis in sea urchin embryos
Protein synthesis can be regulated at a number of cellular levels. I have examined how modifications to specific components of the protein synthetic machinery are involved in regulating the efficiency of initiation of translation during early sea urchin embryogenesis. It is demonstrated that Ca{sup 2+} concentrations exceeding 500 uM cause the inhibition of protein synthesis in cell-free translation lysates prepared from sea urchin embryos. Specific changes in the state of phosphorylation of at least 8 proteins occur during this Ca{sup 2+}-mediated repression of translation. Analysis of these proteins has indicated that, unlike mammalian systems, there is no detectable level of Ca{sup 2+}-dependent phosphorylation of the {alpha}subunit eIF-2. Two of the proteins which do become phosphorylated in response to Ca{sup 2+} are calmodulin and an isoelectric form of sea urchin eIF-4D. In addition, 2 proteins which share similarities with kinases involved in the regulation of protein synthesis in mammalian cells, also become phosphorylated. I have investigated the consequences of changes in eIF-4D during sea urchin embryogenesis because it has been proposed that a polyamine-mediated conversion of lysine to hypusine in this factor may enhance translational activity. It is demonstrated that ({sup 3}H) spermidine-derived radioactivity is incorporated into a number of proteins when sea urchin embryos are labeled in vivo, and that the pattern of individual proteins that become labeled changes over the course of the first 30 hr of development.
- Research Organization:
- Wesleyan Univ., Middletown, CT (USA)
- OSTI ID:
- 5649361
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Phosphorylation of mammalian initiation factor eIF-4B
Regulation of protein synthesis during sea urchin early development
Related Subjects
CALCIUM COMPOUNDS
BIOCHEMICAL REACTION KINETICS
PROTEINS
BIOSYNTHESIS
SEA URCHINS
ONTOGENESIS
BIOCHEMISTRY
EMBRYOS
INHIBITION
PHOSPHORYLATION
SPERMIDINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
AMINES
ANIMALS
AQUATIC ORGANISMS
CHEMICAL REACTIONS
CHEMISTRY
ECHINODERMS
HYDROGEN COMPOUNDS
INVERTEBRATES
ISOTOPE APPLICATIONS
KINETICS
ORGANIC COMPOUNDS
REACTION KINETICS
SYNTHESIS
550201* - Biochemistry- Tracer Techniques