TABLE 1.

Partition coefficients of the probes between l_o and l_d, , and gel and fluid, , phases

Probe	in POPC/PSM/Chol	in POPC/PCer
DPH	1.05 ± 0.08*	∼0*§
NBD-DOPE	1.20 ± 0.06†	∼0†§
NBD-DPPE	3.68 ± 0.55†	∼0†§
Rho-DOPE	0.28 ± 0.08‡	∼0‡§
t-PnA	0.88 ± 0.05†	4.50 ± 0.60†

^*K_p was determined from Eq. 4.

^†K_p was determined from Eq. 1.

^‡K_p was determined from Eq. 3.

^§The photophysical parameters of these probes remain almost unchanged, with PCer-gel fraction indicating that their partition into the PCer-gel phase is very low.