Phosphorylation of the protein encoded by the first open reading frame of the MDG4 transposable element (gypsy) by homologous and heterologous caseinkinases type 2

Homogeneous casein kinase type 2 (CK2) was obtained from oocytes of Rana te mporaria and cells of Drosophila melanogaster by chromatography on heparin- Sepharose, phosphocellulose, and Mono Q columns using a Pharmacia FPLC syst em. The procedure was first successfully used for the purification of CK2 f rom the Drosophila melanogaster cell culture. It has been shown that the pr otein encoded by the first open reading frame (ORF) of the gypsy transposab le element (MDG4) is an effective protein substrate both for homologous and heterologous CK2 from the oocytes of Rana temporaria in vitro. Both enzyme s catalyze the incorporation of two moles of phosphate per mole of protein. The K-m and V-max values for the reaction catalyzed by CK2 from the Drosop hila cell culture were 32.5 +/- 2.1 nM and 70.97 +/- 1.89 nmol/min per mug, respectively, and for CK2 from oocytes, these values were 37.6 +/- 2.8 nM and 66.02 +/- 2.15 nmol/min per mug, respectively.