Figure 4

FRET measurements disclose interaction between TMD and FP in an antiparallel manner. The efficiency of FRET between pyrene and NBD labeled to the N- and C-termini of TMD and FP peptides in different combinations is compared to determine the orientation of the TMD:FP complex. FRET efficiency is larger for the donor and acceptor fluorophores attached to the opposite ends of TMD and FP. It is also noted that the interaction between FP and TMD is stronger at pH 5.0 than at 7.4 as reflected by greater transfer efficiency.