Fig. 3.

Wild-type and mutant PDX1 half-life MIN6 β-cells were transduced with adenoviruses encoding wild-type c-myc-tagged-PDX1 (A) or S269A and S269E mutants (B, C) and their respective protein half-life was measured. Total extracts prepared at the indicated times of chase were immunoprecipitated with anti-c-myc antibody. PDX1 protein was detected by fluorography. The intensity of radioactive bands was measured and plotted as a percentage of the initial band intensity (0 h) with Optiquant in a Cyclone (Perkin–Elmer) phospho imager storage system. No significant difference in turnover rate was found between wild-type PDX1 and the mutants. The estimated half-lives of WT PDX1 and mutants S269A, S269E were extrapolated by non linear regression from the exponential decay curve fitted to the data points using SigmaPlot 11.0 (Systat Software Inc., San Jose, CA USA). Data points represent the mean ± SEM of three to four experiments.