A novel cholesterol transfer protein in cardiac sarcolemma. Purification and initial characterization.

In contrast to several sterol carrier proteins isolated from soluble cytosolic fractions, a cholesterol transfer protein (CHTP) with an apparent molecular weight of 73,000 was isolated from a cardiac sarcolemmal fraction by detergent solubilization, column chromatography, and preparative electrophoresis using nondissociating polyacrylamide gels. This protein must be reconstituted into an artificial membrane in order to mediate cholesterol transfer activity. For the expression of its full activity, CHTP must also be present in the membrane in a multimeric form, since the monomer was shown not to be active. We believe this novel protein might represent an important molecule in the regulation of the homeostasis of cholesterol in cardiac sarcolemma.