Human leukemia CEM C-1 cells possess a high affinity binding site for farnesol

Binding of 15-carbon isoprenoid farnesol in human acute leukemia CEM C-1 cells has been studied by addition of radio-labeled isoprenoid to cell growth medium. Significant time-dependent accumulation of the cell-associated radioactivity was detected at 37 degrees C. When experiments were carried out at 4 degrees C, about 10 times decrease in cell labeling was observed. In contrast, binding of farnesol by the liposomes prepared from cellular lipids was independent of the temperature. When binding experiments were performed in the presence of the excess of unlabeled farnesol, a saturable specific component was separated from the total binding. Analysis of the specific binding revealed about 335,000 binding sites per cell with Kd of 5.9 x 10(-8) M. The data suggest that CEM C-1 cells may possess receptors capable of binding farnesol.