Transient Increase of a Protein Kinase Activity Identified to CK2 during Sea Urchin Development

Abstract

Using GST-EF-1 δ as an exogenous substrate, and EF-1 δ kinase activity was shown to increase transiently during early development of sea urchin embryos. The basal activity of EF-1 δ kinase in unfertilized eggs was 150 fmoles/min/mg protein. The activity began to increase 10 h after fertilization and reached its maximum level (8.4 × basal) at 24 h. The activity then declined to twice the basal value at 72 h post-fertilization. The EF-1 δ kinase activity was identified to a CK2-type enzyme on the basis of its substrate specificity for EF-1 δ, crude casein and β casein, its inhibition by heparin, DRB, 2,3-bisphosphoglycerate, and its stimulation by spermine, spermidine, and polylysin. Furthermore, the activity was inhibited by the synthetic peptide RRREEETEEE specific for CK2. DRB (200 μM) and 2,3-bisphosphoglycerate (2.5 mM) blocked or delayed the transition from blastula to gastrula of the embryos, suggesting a role for the kinase in early development.