FIGURE 5.

Effect of ATP on the conformation of the transmembrane domain of the E₁PCa analog. Specific incorporation of [¹²⁵I]TID-PC/16 to PMCA was determined as a function of increasing ATP concentrations in the presence of 100 μm free Ca²⁺ plus 50 μm La^III. Specific incorporation of the probe into PMCA in the presence of 2 mm EGTA was taken as 100%. Results were approximately constant (continuous line, but see “Discussion”), and a precise value of K_x could not be determined (see Table 1, Reaction ix).