Figure 1.

p21-Dependent changes in the total activity of OGDHC (A–D) and its partition into the holo- (E,F) and apoenzymes (I–L) at the exposure of A549 cells to varied thiamine/ThDP levels. A549^wt or A549^p21- cells were cultured in DMEM prepared either with 4 mg/L thiamine hydrochloride (Control, A,B,E,F,I,J) or without thiamine (Thiamine deficiency, C,D,G,H,K,L). Analysis was made 24 h after the media were exchanged for those without (gray columns) or with 5 mM ThDP (black columns). The OGDHC partition into the apo- and holoenzymes was determined as described in the text and Materials and Methods. Under the graphs E-H the OGDHC holoenzyme activities are shown as % of total OGDHC activities (“%holo”). The data of at least three independent experiments are presented as mean ± SEM. Statistical significance of the differences between all the groups (shown in full in Table 1) was determined by two-way ANOVA followed by Tukey’s post hoc test. On the graphs, only the differences due to the ThDP/thiamine variations are indicated. The p-values above the horizontal lines or the grey bars characterize the changes due to the ThDP addition or thiamine deficiency, correspondingly.