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The presence of scavenger receptor class B type I in the small intestine brush border membrane was investigated. Experimental results confirmed this presence and showed that scavenger class B type I facilitates the uptake of dietary cholesterol from either bile salt micelles or phospholipid vesicles. The receptor was also found to be capable of functioning as a port for several additional classes of lipids such as phospholipids, cholesteryl esters and triacylglycerols.

Reconstitution of the cholesterol transport activity of rabbit brush border membrane (BBM) artificial membrane system was done to establish the effect of hydrolysis of lipids to monoacylglycerols and fatty acid in the uptake of triacylglycerols by the brush border membrane. Results have shown that sterol transport protein was integrated into the lipid bilayer as evidenced by density gradient centrifugation on a Ficoll gradient.

The differences between cholesterol and plant sterol sitosterol uptake in the brush border was investigated through the utilization of comparative study of sterol uptake by brush border membrane vesicles and sterol absorption by Caco-2 cells. Results have shown that detection of possible inhibitory effects on cholesterol uptake can occur only at the presence of large amounts of sitosterol contents in the donor. The mechanism of energy-independent uptake of sitosterol mimics that of the cholesterol.

The protein present in the lumenal side of the brush border membrane vesicles catalyzes the chain cholesteryl ester and ether absorption. The protein-mediated absorption of cholesteryl ester follows a second-order reaction in the first phase. Autoproteolysis induces the release of water-soluble form of the protein. The free and esterified cholesterol exchange between the two populations of small unilamellar phospholipid vesicles is catalyzed by the protein.