Cholesterol utilization sterol carrier protein 2, participation

Participation of sterol carrier proteins in cholesterol biosynthesis, utilization and... 

Investigations conducted in our laboratory [3] and by Ritter and Dempsey [11] resulted in the proposal that a sterol carrier protein, present in rat liver cytosol, was required for the conversion of squalene to cholesterol by liver microsomal enzymes. Later, it was shown that rat liver cytosol contains two proteins which are required for the microsomal conversion of squalene to cholesterol [5,12]. Sterol carrier proteinj (SCPi) participates in the microsomal conversion of squalene to lanosterol, while sterol carrier protein 2 (SCP2) participates in the microsomal conversion of lanosterol to cholesterol. In addition, SCP2 also participates in key steps in the utilization of cholesterol as well as in the intracellular transfer of cholesterol between cellular organelles. 

Fig. 8 is a schematic diagram of a cell which shows the known sites in which sterol carrier proteins are involved in cholesterol biosynthesis, utilization and intracellular transfer. SCP, participates in the conversion of squalene to lanosterol and SCP2 participates in the conversion of lanosterol to cholesterol, the conversion of cholesterol to cholesterol ester by ACAT, and probably also in the conversion of cholesterol to 7a-hydroxycholesterol. SCPj transfers cholesterol from cytoplasmic lipid inclusion droplets to mitochondria in the adrenal and SCPj also translocates cholesterol from the outer to the inner mitochondrial membrane. 

Significant progress has been made concerning the participation of sterol carrier proteins in cholesterol biosynthesis, utilization and intracellular transfer. It is anticipated that in the coming years research will focus not only on additional aspects of intracellular sterol transfer, but also on the molecular mechanisms involved in the binding of sterols to SCPj. 

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See also in sourсe #XX -- [ ]

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