Mouse embryos at various stages of development were used to study the relationship of protein kinase activities with normal embryogenesis. Casein kinase II (CKII) activity in developing mouse embryos shows a 3-4-fold activity increase at day 12 of gestation. Together with the CKII activity, increased phosphorylation of a 110-kDa protein is observed. Treatment of the embryo extracts with heparin, a highly specific inhibitor of CKII activity, results in a drastic reduction of the 110-kDa protein phosphorylation indicating that the protein might be a CKII-specific substrate. Rapidly proliferating mouse tumour cells also show an enhanced CKII activity. Here too, a 110-kDa phosphoprotein was the major phosphoryl acceptor. Partial proteolytic digestion shows that both proteins are identical. Other protein kinases tested (cAMP- and cGMP-dependent protein kinases) only show a basal level of enzyme activity with minor alterations throughout the different stages of embryogenesis investigated.
European Journal of Biochemistry, 1986, Vol 161, Issue 3, p. 733-738
Animals; Autoradiography; Carcinoma, Krebs 2; Casein Kinases; Centrifugation, Density Gradient; Embryo, Mammalian; Embryonic and Fetal Development; Mice; Molecular Weight; Peptide Mapping; Phosphoproteins; Phosphorylation; Protein Kinases