Fig. 2. (A) An overview of DdNek2 deletion mutants. (B) Catalytic activity of MBP-DdNek2 and its mutants. The substrates were /ß-casein, the recombinant C-terminal DdNek2 fragment MBP-258-C and BSA (negative control). DdNek2 and its C-terminal deletion constructs were analyzed on the same gel to allow comparison of their catalytic activity. Proteins of each kinase reaction precipitated with TCA were separated by SDS-gel electrophoresis, stained with Coomassie and subjected to autoradiography. The molecular mass (kDa) of standard proteins is indicated on the left and the position of the individual protein bands on the right. The kinase derivatives and substrates used are given at the bottom. Nek refers to DdNek2, K33R to MBP-DdNek2-K33R, Cas to /ß-casein, 258C to MBP-258-C, 315N to MBP-315-N and 267N to MBP-267-N.