A comment on the localization of cyanine dye binding to brush-border membranes by the fluorescence quenching of n-(9-anthroyloxy) fatty acid probes.

This work comments on the location and orientation of 3,3'-dipropylthiodicarbocyanine (diS-C3-(5)) in renal brush-border membrane vesicles (RBBMV) (Cabrini, G. and Verkman, A.S. (1986) Biochim. Biophys. Acta 862, 285-293) evaluated from collisional quenching of n-(9-anthroyloxy)stearic acid (n-AS) fluorescence. At variance with these authors, it is concluded that the quenching is due to resonance energy transfer. It is also shown that the fluorescence data are not clear evidence for the reported monomer and dimer locations.