Figure 5.

Effect of GTP (1 mM) on IPAG binding to the sigma-1 receptor. IPAG competition binding curve with 30 nM [³H]-(+)-pentazocine to permeabilized MDA-MB-468 cells washed with TBS to remove any endogenous GTP. Assays were performed in the absence (solid squares) or presence (open circles) of GTP. Competition binding to intact cells is also shown (solid diamonds). Error bars show SEM, n = 5.