The N-terminal fragment of SOK1 can induce cell death with high
efficiency, and this is dependent on its kinase activity and amino acids
275-292. M2-flagged versions of SOK1ΔC,
SOK1ΔCK49R, SOK1ΔCT174A, and
SOK1ΔC4A were transfected into HEK293 cells. A, the
levels of expression of the different mutants were determined by Western
blotting using anti-M2 antibody. B, the kinase activity of each
mutant toward the unspecific substrate myelin basic protein (MBP) was
determined after immunoprecipitation with the M2 antibody. C, the
ability of each mutant to induce cell death was assessed by determining the
percentage of non-viable cells by trypan blue exclusion. Shown is the mean and
S.D. of four independent experiments. *, p < 0.05
versus SOK1ΔC. WT, wild-type.