Distribution of elongation factor 2 between particulate and soluble fractions of the brine shrimp Artemia during early development

Abstract
The ADP-ribosylation of elongation factor 2 (EF-2) in vitro was used to quantitate EF-2 and to determine its subcellular distribution in extracts of Artemia embryos at different stages of development. In extracts from dormant cysts of Artemia 40–45% of EF-2 is complexed to macromolecules smaller than ribosomes, whereas the remainder is soluble or free in the cytosol. During early development the amount of "complexed" EF-2 decreases markedly concomitant with an increase in the pool of soluble EF-2. Complexed EF-2 was found to be associated with macromolecules which sediment at 16S–20S and 40S–50S and not with monoribosomes or polyribosomes as reported for mammalian systems. The data show that the decrease in complexed EF-2 is associated with the resumption of development in Artemia.