Figure 7. The DRMs containing α_s1-casein are sensitive to cholesterol depletion.

Membrane-bound organelles in PNS or purified rough microsomes fractions were incubated in non-conservative buffer without Tween 20 and saponin, in the absence or the presence of the indicated concentration of mßCD for 30 minutes at 37°C. After centrifugation, supernatant (S) and pellet (P) were analysed via SDS-PAGE followed by immunoblotting with antibodies against mouse milk proteins or ERLIN2. For each type of membranes, three independent experiments are shown. The protein concentration in the analysis of the PNS 1 was twice lower than for all other samples and most of the scans showing α_s1-casein signal were taken from overexposed films for a better display of the large reduction of α_s1-casein present in the membrane pellet after cholesterol extraction by mßCD. Relative molecular masses (kDa) are indicated. im. α_s1-cas: immature α_s1-casein; m. α_s1-cas: mature α_s1-casein.