Luteinized rat ovaries contain a sterol carrier protein

Highly luteinized rat ovaries contain a soluble 13,000 mol wt factor which binds [3H]cholesterol and enhances cholesterol transfer from phospholipid vesicles to mitochondria. The ovarian cholesterol transfer protein was purified 1200-fold. It has a basic isoelectric point, is heat stable, and has an amino acid composition similar to that reported for rat liver sterol carrier protein2. Antisera raised against preparations of rat liver sterol carrier protein2 precipitated labeled cholesterol associated with the ovarian 13,000 mol wt fraction. A line of partial identity was obtained when the ovarian fractions and purified rat liver sterol carrier protein2 were run against these antisera in double immunodiffusion. We conclude that luteinized rat ovaries contain a sterol carrier protein with properties similar to hepatic sterol carrier protein2. This protein may facilitate the intracellular distribution of cholesterol in ovarian cells.