Identification of gonadotropin inducible, high density lipoprotein receptors in the solubilized membranes from rat ovary.

Specific receptors for high density lipoproteins (HDL3) were solubilized from membranes of rat corpus luteum using different detergents. Among the detergents tested, octyl-beta-D-glucoside (40 mM) was most effective with respect to recovery of binding activity. The receptor activity released into 105,000 X g supernatant, can be assayed directly or with the precipitate obtained after dilution of the soluble supernatant. The 125I-HDL3 binding activity in the precipitated extract was linear with time, proportional to the amount of protein in the incubation mixture and saturable with increasing concentrations of 125I-HDL3. The solubilized receptor has an equilibrium dissociation constant (Kd) of 21.2 micrograms/ml and the binding activity was insensitive to Ca+2, EDTA and NaCl. These properties are similar to the membrane associated receptor. Administration of gonadotropin induced the HDL3 receptor in the solubilized membranes, suggesting that this receptor represents the physiologic receptor in the ovary.