Figure 3. Kinetics of recombinant CD98 phosphorylation by casein kinase 2.

Phosphorylation reactions were performed using different concentrations of recombinant CD98 and constant amounts of casein kinase 2 (CK2, 50 ng) and [γ-³²P]ATP (2 µCi). Myelin basic protein (MBP), used as a positive control, was phosphorylated under the same condition. The samples were analysed by SDS-PAGE, and radiolabeled bands were detected and quantified using a Storm Typhoon 9200 PhosphorImager. The kinetic constant K _m was determined from a Michalis-Menten plot using an Enzyme Kinetic Program. Data are means±S.E.M of three determinations.