Fig. S1.

TBZ is a mixed-type inhibitor. Noncompetitive inhibitors are a special rare case of mixed inhibitors in which only the V_max is changed. In the case of TBZ, the K_M values change about twofold, whereas the V_max changes 10-fold (Inset). In this manuscript, as well as in previous literature, the term “noncompetitive inhibitor” is freely used for the mode of action of TBZ. In the experiment shown in this figure, cells were incubated with increasing concentrations of [³H]serotonin without TBZ (solid black square) or with 500 nM TBZ (solid red circle) or 1,250 nM TBZ (solid blue triangle). K_M and V_max values shown in the table were calculated using Origin 9.2 software (OriginLab) and are averages of three experiments.