FIGURE 3.

Experimental order parameter profiles and average chain length of (A) POPC-d₃₁ and (B) PSM-d₃₁ in a POPC/PSM/Chol (4/4/2) mixture in the absence and in the presence of 9 mol% 5-HT determined from ²H NMR experiments carried out at a temperature of 30°C. In the presence of 5-HT, two phases with distinctly different order parameters are observed. Phase I represents a disordered and phase II an ordered phase. The insets show the projected average chain length <L> of the palmitoyl chain of POPC or PSM in the absence (black bars) and in the presence of 9 mol% 5-HT (phase I filled colored bars, phase II empty colored bars). The error bars in the insets represent the error estimate of the chain length determination from ²H NMR spectra (Holte et al., 1996).