Purification of the low density lipoprotein receptor, an acidic glycoprotein of 164,000 molecular weight.

This paper describes a rapid two-step procedure for the purification of the low density lipoprotein receptor from bovine adrenal cortex membranes. After solubilization with nonionic detergents, the receptor adheres tightly to a DEAE-cellulose column at pH 6. Following elution from DEAE-cellulose, detergent is removed, leaving the receptor in a soluble form. The receptor is then subjected to affinity chromatography on low density lipoprotein coupled to Sepharose 4B. The receptor is eluted with suramin, a newly-found inhibitor of low density lipoprotein-receptor interactions. This procedure yields a single protein with a molecular weight of 164,000. The same protein is also isolated when the crude DEAE-cellulose fraction is applied to an immunoaffinity column containing a monoclonal antibody directed against the receptor. The 164,000-dalton receptor protein has an acidic isoelectric point of 4.6, which rises to 4.8 after extensive treatment with neuraminidase. The purified receptor retains all of the binding properties of the receptor of intact cells and crude membranes.