title: The binding of [3H]-prostacyclin to membranes of a neuronal somatic hybrid.
abstract: 1 [3H]-prostacyclin bound to a washed membrane preparation of the NCB-20 neuronal hybrid cell line. 2 Kinetic analysis of [3H]-prostacyclin binding suggested a simple, non-cooperative bimolecular interaction between the ligand and a single receptor population. The equilibrium dissociation constant was 16.6 nM, and binding at a saturating [3H]-prostacyclin concentration enabled the receptor density of 2.57 x 10(5) receptor molecules per cell to be calculated. 3 At 20 degrees C the rate constant for the forward reaction (K+1) was 2.26 x 10(5) M-1 S-1, and the rate constant for the dissociation of the ligand-receptor complex (k-1) was 3.85 x 10(-3) S-1. Thus the dissociation constant (k-1/k+1) was 17.0 nM. 4 Prostaglandin E1 and prostacyclin compete for a single receptor in these cells, and comparison of other prostaglandins as inhibitors of [3H]-prostacyclin binding revealed some of the structural requirements for high-affinity occupation of prostacyclin receptors.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D011464:Epoprostenol / Q000378:metabolism*; D006822:Hybrid Cells / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D009474:Neurons / Q000378:metabolism; D011453:Prostaglandins / Q000378:metabolism*; D011458:Prostaglandins E / Q000378:metabolism; D011869:Radioligand Assay; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011982:Receptors, Prostaglandin / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014316:Tritium
chemical_list: D011453:Prostaglandins; D011458:Prostaglandins E; D011956:Receptors, Cell Surface; D011982:Receptors, Prostaglandin; D014316:Tritium; D011464:Epoprostenol; D000262:Adenylyl Cyclases