The participation of sterol carrier protein2 in cholesterol esterification in rat adrenal microsomes.

The effect of sterol carrier protein2 (SCP2) purified from rat liver on the formation of cholesterol esters by acyl-CoA: cholesterol acyl-transferase (ACAT: EC 2.3.1.26) in rat adrenal microsomes was studied. The rate of incorporation of [1-14C]oleoyl-CoA into cholesteryl oleate was determined in the presence or absence of exogenously added cholesterol or SCP2, or both. The addition of SCP2 had no effect on the formation of cholesterol esters from endogenous cholesterol by ACAT in rat adrenal microsomes. In contrast, the formation of cholesterol esters from exogenous cholesterol by ACAT was dose-dependently increased by the addition of SCP2. These experiments showed that SCP2 had an enhancing effect on cholesterol esterification by ACAT in rat adrenal microsomes most likely by modulating the availability of exogenous cholesterol and that SCP2 may participate in the formation of cholesterol esters in the rat adrenal gland.