Cholesterol esterase bound to intestinal brush border membranes does not accelerate incorporation of micellar cholesterol into absorptive cells.

We confirmed that cholesterol esterase accelerated the incorporation of unesterified cholesterol solubilized in bile salt micelles into differentiated Caco-2 cells under various experimental conditions. Rat pancreatic juice and bovine cholesterol esterase increased the incorporation of micellar cholesterol into rat intestinal brush border membranes. The incorporation of micellar cholesterol was not changed in the brush border membranes enriched in and depleted of cholesterol esterase. The results suggest that the accelerated incorporation of micellar cholesterol by cholesterol esterase into absorptive cells is not mediated by the enzyme bound to the brush border membranes.