Transfer of cholesterol and sitosterol from rat intestinal brush border membranes to phospholipid liposomes: Effects of SCP₂

Regarding the transport of absorbed sterols to endoplasmic reticulum in intestinal mucosal cells, transfer of cholesterol and sitosterol from rat intestinal brush border membranes to phospholipid liposomes was investigated. Transfer of sitosterol from brush border membranes to liposomes was significantly slower than that of cholesterol. Sitosterol transfer increased dose-dependently with the addition of sterol carrier protein₂ (SCP₂), but only a transient increase was observed with cholesterol. The results suggest that a slower rate of transfer of sitosterol than cholesterol from brush border membranes to the intracellular site of use may be one mechanism by which sitosterol transport into lymph is delayed, as observed previously in the rat intestine. SCP₂ may not essentially participate in the transfer of absorbed cholesterol.