Elongation factor 2 from Artemia salina embryos and its affinity for ribosomes

Crude extracts from Artemia salina undeveloped embryos do not contain detectable elongation-factor-2 (EF2) kinase and endogenous ADP-ribosylating activities. Accordingly, EF2 purified from this source is an enzyme relatively free from phosphorylated and ADP-ribosylated forms. Endogenous ADP-ribosyltransferase activity appears only after purification of EF2. The affinities of EF2 and of ADP-ribosyl-EF2 for ribosomes from A. salina undeveloped embryos have been calculated by measuring the ability of the factors to inhibit the N-glycosidase activity of ricin on ribosomes.