FIGURE 5.

Quenching of KcsA fluorescence by brominated phospholipids. KcsA was reconstituted into bilayers containing mixtures of nonbrominated lipid and the corresponding brominated lipid at pH 7.2. Fluorescence intensities are expressed as a fraction of the fluorescence for KcsA reconstituted in the nonbrominated lipid. Phospholipids were as follows: (○), phosphatidylserine; (□), phosphatidic acid; and (▵), cardiolipin. The lines show fits to Eq. 1 giving the values for n listed in Table 1. The buffer was 20 mM HEPES and 1 mM EGTA at pH 7.2.