Fig. 4

The TKTL1-TKT heterodimer possesses asymmetric transketolase activities. a Schematic diagram of the four transketolase activities. b The absolute specific transketolase activities of recombinant TKTL1 and TKT were determined and then compared. Data are shown as average of 3 independent experiments, presented as means ± SEM, two-tailed Students’ t test, ***p < 0.001. c Specific transketolase activities of the recombinant TKTL1-TKT heterodimer and TKT-TKT homodimer were determined and then compared. Data are presented as means ± SEM of three independent experiments, two-tailed Student’s t test, ***p < 0.001, **p < 0.01, *p < 0.05. d Substrate binding to the TKTL1/TKT heterodimer and TKT homodimer were analyzed via SPR. Mean values with SEM are reported, Student’s t test, ***p < 0.001, **p < 0.01, *p < 0.05, ns not significant vs the corresponding control group. e, f Relative (to total transketolase activity) R5P removal activity (reaction 1; e) and R5P production activities (reaction 3; f) at different phases of the cell cycle were determined. Different cell cycle phases were achieved by releasing double thymidine (upper panel) and RO3306 (lower panel)-synchronized HeLa cells. Data are presented by means ± SEM of three independent experiments