title: Sedimentation behavior of solubilized gonadotropin receptor from plasma membranes of bovine corpus luteum.
abstract: The gonadotropin receptors associated with plasma membrane fractions were solubilized by detergents, including Triton X-100, Lubrol WX, Lubrol PX and sodium deoxycholate before and after equilibration with 125I-labelled human chorionic gonadotropin. The binding activity remained in solution even after centrifugation at 300 000 X g for 3 h. The solubilized gonadotropin receptor or gonadotropin receptor complex was characterized by gel filtration and sucrose density gradient centrifugation. Sucrose density gradient centrifugation of solubilized gonadotropin-receptor complex in the presence of Triton X-100 had a sedimentation coefficient of 6.5 S whereas the solubilized uncomplexed receptor had a sedimentation coefficient of 5.1 S. In the absence of the detergent, solubilized hormone receptor complex from plasma membrane fractions I and II sedimented with an apparent sedimentation coefficient of 6.6 S and 7.4 S, respectively. Similarly, the free receptor also showed higher sedimentation profile with an apparent sedimentation coefficient of 6.7 S for fraction I and 7.2 S for fraction II. Treatment of plasma membranes with phospholipase A and C inhibited the binding of 125I-labelled human chorionic gonadotropin in a dose dependent manner, whereas phospholipase D was without any effect. Doses of 1.4 mI. U. of phospholipase A or 0.6 mI.U. of phospholipase C were required to produce 50% inhibition of the binding activity. These phospholipases had no effect on the preformed 125I-labelled human chorionic gonadotropin-receptor complex nor on the sedimentation profile of solubilized gonadotropin receptor complex.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism*; D002499:Centrifugation, Density Gradient; D006063:Chorionic Gonadotropin / Q000378:metabolism; D002850:Chromatography, Gel; D003338:Corpus Luteum / Q000378:metabolism* / Q000648:ultrastructure; D003840:Deoxycholic Acid / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D005260:Female; D006062:Gonadotropins / Q000378:metabolism*; D010740:Phospholipases / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000187:drug effects*
chemical_list: D006063:Chorionic Gonadotropin; D003902:Detergents; D006062:Gonadotropins; D011956:Receptors, Cell Surface; D003840:Deoxycholic Acid; D010740:Phospholipases