Identification of a new isoform of eEF2 whose phosphorylation is required for completion of cell division in sea urchin embryos

► Presence of two isoforms of translational elongation factor EF2 in sea urchin embryos. ► Phosphorylation of each isoform is differentially regulated after fertilization. ► Dephosphorylation of both isoforms correlates with protein synthesis increase. ► Proper cell division depends on the re-phosphorylation of the lower eEF2 isoform.